help_topic_id name help_category_id description example url
0 JOIN 6 MySQL supports the following JOIN syntaxes for the table_references part of SELECT statements and multiple-table DELETE and UPDATE statements: table_reference, table_reference table_reference [INNER | CROSS] JOIN table_reference [join_condition] table_reference STRAIGHT_JOIN table_reference table_reference LEFT [OUTER] JOIN table_reference join_condition table_reference NATURAL [LEFT [OUTER]] JOIN table_reference { OJ table_reference LEFT OUTER JOIN table_reference ON conditional_expr } table_reference RIGHT [OUTER] JOIN table_reference join_condition table_reference NATURAL [RIGHT [OUTER]] JOIN table_reference table_reference is defined as: tbl_name [[AS] alias] [[USE INDEX (key_list)] | [IGNORE INDEX (key_list)] | [FORCE INDEX (key_list)]] join_condition is defined as: ON conditional_expr | USING (column_list) mysql> SELECT table1.* FROM table1 -> LEFT JOIN table2 ON table1.id=table2.id -> WHERE table2.id IS NULL;  
1 HEX 23 HEX(N_or_S) If N_OR_S is a number, returns a string representation of the hexadecimal value of N, where N is a longlong (BIGINT) number. This is equivalent to CONV(N,10,16). From MySQL 4.0.1 and up, if N_OR_S is a string, returns a hexadecimal string of N_OR_S where each character in N_OR_S is converted to two hexadecimal digits. mysql> SELECT HEX(255); -> 'FF' mysql> SELECT 0x616263; -> 'abc' mysql> SELECT HEX('abc'); -> 616263  
2 REPLACE 23 REPLACE(str,from_str,to_str) Returns the string str with all occurrences of the string from_str replaced by the string to_str. mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww'); -> 'WwWwWw.mysql.com'  
3 REPEAT 23 REPEAT(str,count) Returns a string consisting of the string str repeated count times. If count <= 0, returns an empty string. Returns NULL if str or count are NULL. mysql> SELECT REPEAT('MySQL', 3); -> 'MySQLMySQLMySQL'  
4 CONTAINS 11 Contains(g1,g2) Returns 1 or 0 to indicate whether or not g1 completely contains g2.    
5 SRID 19 SRID(g) Returns an integer indicating the Spatial Reference System ID for the geometry value g. In MySQL, the SRID value is just an integer associated with the geometry value. All calculations are done assuming Euclidean (planar) geometry. mysql> SELECT SRID(GeomFromText('LineString(1 1,2 2)',101)); +-----------------------------------------------+ | SRID(GeomFromText('LineString(1 1,2 2)',101)) | +-----------------------------------------------+ | 101 | +-----------------------------------------------+  
6 CURRENT_TIMESTAMP 14 CURRENT_TIMESTAMP CURRENT_TIMESTAMP() CURRENT_TIMESTAMP and CURRENT_TIMESTAMP() are synonyms for NOW().    
7 VARIANCE 12 VARIANCE(expr) Returns the population standard variance of expr. This is an extension to standard SQL, available in MySQL 4.1 or later. As of MySQL 5.0.3, the standard SQL function VAR_POP() can be used instead.    
8 VAR_SAMP 12 VAR_SAMP(expr) Returns the sample variance of expr. That is, the denominator is the number of rows minus one. This function was added in MySQL 5.0.3.    
9 CONCAT 23 CONCAT(str1,str2,...) Returns the string that results from concatenating the arguments. Returns NULL if any argument is NULL. May have one or more arguments. If all arguments are non-binary strings, the result is a non-binary string. If the arguments include any binary strings, the result is a binary string. A numeric argument is converted to its equivalent binary string form. mysql> SELECT CONCAT('My', 'S', 'QL'); -> 'MySQL' mysql> SELECT CONCAT('My', NULL, 'QL'); -> NULL mysql> SELECT CONCAT(14.3); -> '14.3'  
10 GEOMETRY HIERARCHY 24 Geometry is the base class. It's an abstract class. The instantiable subclasses of Geometry are restricted to zero-, one-, and two-dimensional geometric objects that exist in two-dimensional coordinate space. All instantiable geometry classes are defined so that valid instances of a geometry class are topologically closed (that is, all defined geometries include their boundary). The base Geometry class has subclasses for Point, Curve, Surface, and GeometryCollection: --- Point represents zero-dimensional objects. --- Curve represents one-dimensional objects, and has subclass LineString, with sub-subclasses Line and LinearRing. --- Surface is designed for two-dimensional objects and has subclass Polygon. --- GeometryCollection has specialized zero-, one-, and two-dimensional collection classes named MultiPoint, MultiLineString, and MultiPolygon for modeling geometries corresponding to collections of Points, LineStrings, and Polygons, respectively. MultiCurve and MultiSurface are introduced as abstract superclasses that generalize the collection interfaces to handle Curves and Surfaces. Geometry, Curve, Surface, MultiCurve, and MultiSurface are defined as non-instantiable classes. They define a common set of methods for their subclasses and are included for extensibility. Point, LineString, Polygon, GeometryCollection, MultiPoint, MultiLineString, and MultiPolygon are instantiable classes.    
11 CHAR FUNCTION 23 CHAR(N,...) CHAR() interprets the arguments as integers and returns a string consisting of the characters given by the code values of those integers. NULL values are skipped. mysql> SELECT CHAR(77,121,83,81,'76'); -> 'MySQL' mysql> SELECT CHAR(77,77.3,'77.3'); -> 'MMM'  
12 DATETIME 1 A date and time combination. The supported range is '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. MySQL displays DATETIME values in 'YYYY-MM-DD HH:MM:SS' format, but allows you to assign values to DATETIME columns using either strings or numbers.    
13 LOWER 23 LOWER(str) Returns the string str with all characters changed to lowercase according to the current character set mapping (the default is ISO-8859-1 Latin1). mysql> SELECT LOWER('QUADRATICALLY'); -> 'quadratically'  
14 MONTH 14 MONTH(date) Returns the month for date, in the range 1 to 12. mysql> SELECT MONTH('1998-02-03'); -> 2  
15 TINYINT 1 TINYINT[(M)] [UNSIGNED] [ZEROFILL] A very small integer. The signed range is -128 to 127. The unsigned range is 0 to 255.    
16 ISCLOSED 18 IsClosed(ls) Returns 1 if the LineString value ls is closed (that is, its StartPoint() and EndPoint() values are the same). Returns 0 if ls is not closed, and -1 if it is NULL. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT IsClosed(GeomFromText(@ls)); +-----------------------------+ | IsClosed(GeomFromText(@ls)) | +-----------------------------+ | 0 | +-----------------------------+  
17 MASTER_POS_WAIT 21 MASTER_POS_WAIT(log_name,log_pos[,timeout]) This function is useful for control of master/slave synchronization. It blocks until the slave has read and applied all updates up to the specified position in the master log. The return value is the number of log events it had to wait for to get to the specified position. The function returns NULL if the slave SQL thread is not started, the slave's master information is not initialized, the arguments are incorrect, or an error occurs. It returns -1 if the timeout has been exceeded. If the slave SQL thread stops while MASTER_POS_WAIT() is waiting, the function returns NULL. If the slave is past the specified position, the function returns immediately. SELECT MASTER_POS_WAIT('master_log_file', master_log_pos)  
18 ^ 27 ^ Bitwise XOR: mysql> SELECT 1 ^ 1; -> 0 mysql> SELECT 1 ^ 0; -> 1 mysql> SELECT 11 ^ 3; -> 8  
19 DROP VIEW 24 DROP VIEW removes one or more views. You must have the DROP privilege for each view. You can use the keywords IF EXISTS to prevent an error from occurring for views that don't exist. When this clause is given, a NOTE is generated for each non-existent view. See also : [SHOW WARNINGS, , SHOW WARNINGS]. RESTRICT and CASCADE, if given, are parsed and ignored. DROP VIEW [IF EXISTS] view_name [, view_name] ... [RESTRICT | CASCADE]  
20 DATE OPERATIONS 14 DATE_ADD(date,INTERVAL expr type) DATE_SUB(date,INTERVAL expr type) These functions perform date arithmetic. date is a DATETIME or DATE value specifying the starting date. expr is an expression specifying the interval value to be added or subtracted from the starting date. expr is a string; it may start with a '-' for negative intervals. type is a keyword indicating how the expression should be interpreted. mysql> SELECT '1997-12-31 23:59:59' + INTERVAL 1 SECOND; -> '1998-01-01 00:00:00' mysql> SELECT INTERVAL 1 DAY + '1997-12-31'; -> '1998-01-01' mysql> SELECT '1998-01-01' - INTERVAL 1 SECOND; -> '1997-12-31 23:59:59' mysql> SELECT DATE_ADD('1997-12-31 23:59:59', -> INTERVAL 1 SECOND); -> '1998-01-01 00:00:00' mysql> SELECT DATE_ADD('1997-12-31 23:59:59', -> INTERVAL 1 DAY); -> '1998-01-01 23:59:59' mysql> SELECT DATE_ADD('1997-12-31 23:59:59', -> INTERVAL '1:1' MINUTE_SECOND); -> '1998-01-01 00:01:00' mysql> SELECT DATE_SUB('1998-01-01 00:00:00', -> INTERVAL '1 1:1:1' DAY_SECOND); -> '1997-12-30 22:58:59' mysql> SELECT DATE_ADD('1998-01-01 00:00:00', -> INTERVAL '-1 10' DAY_HOUR); -> '1997-12-30 14:00:00' mysql> SELECT DATE_SUB('1998-01-02', INTERVAL 31 DAY); -> '1997-12-02' mysql> SELECT DATE_ADD('1992-12-31 23:59:59.000002', -> INTERVAL '1.999999' SECOND_MICROSECOND); -> '1993-01-01 00:00:01.000001'  
21 WITHIN 11 Within(g1,g2) Returns 1 or 0 to indicate whether or not g1 is spatially within g2.    
22 WEEK 14 WEEK(date[,mode]) The function returns the week number for date. The two-argument form of WEEK() allows you to specify whether the week starts on Sunday or Monday and whether the return value should be in the range from 0 to 53 or from 1 to 53. If the mode argument is omitted, the value of the default_week_format system variable is used (or 0 before MySQL 4.0.14). See also : [Server system variables]. The following table describes how the mode argument works: First day Mode of week Range Week 1 is the first week... 0 Sunday 0-53 with a Sunday in this year 1 Monday 0-53 with more than 3 days this year 2 Sunday 1-53 with a Sunday in this year 3 Monday 1-53 with more than 3 days this year 4 Sunday 0-53 with more than 3 days this year 5 Monday 0-53 with a Monday in this year 6 Sunday 1-53 with more than 3 days this year 7 Monday 1-53 with a Monday in this year A mode value of 3 can be used as of MySQL 4.0.5. Values of 4 and above can be used as of MySQL 4.0.17. mysql> SELECT WEEK('1998-02-20'); -> 7 mysql> SELECT WEEK('1998-02-20',0); -> 7 mysql> SELECT WEEK('1998-02-20',1); -> 8 mysql> SELECT WEEK('1998-12-31',1); -> 53  
23 LOCK 10 LOCK TABLES locks tables for the current thread. If any of the tables are locked by other threads, it blocks until all locks can be acquired. UNLOCK TABLES releases any locks held by the current thread. All tables that are locked by the current thread are implicitly unlocked when the thread issues another LOCK TABLES, or when the connection to the server is closed. A table lock protects only against inappropriate reads or writes by other clients. The client holding the lock, even a read lock, can perform table-level operations such as DROP TABLE. LOCK TABLES tbl_name [AS alias] {READ [LOCAL] | [LOW_PRIORITY] WRITE} [, tbl_name [AS alias] {READ [LOCAL] | [LOW_PRIORITY] WRITE}] ... UNLOCK TABLES  
24 CHECK 7 Checks a table or tables for errors. CHECK TABLE works for MyISAM and InnoDB tables. For MyISAM tables, the key statistics are updated. As of MySQL 5.0.2, CHECK TABLE also can check views for problems, such as tables that are referenced in the view definition that no longer exist. CHECK TABLE tbl_name [, tbl_name] ... [option] ... option = {QUICK | FAST | MEDIUM | EXTENDED | CHANGED}  
25 RESET SLAVE 7 RESET SLAVE Makes the slave forget its replication position in the master's binary logs. This statement is meant to be used for a clean start: It deletes the *master.info and *relay-log.info files, all the relay logs, and starts a new relay log. Note: All relay logs are deleted, even if they have not been totally executed by the slave SQL thread. (This is a condition likely to exist on a replication slave if you have issued a STOP SLAVE statement or if the slave is highly loaded.) Connection information stored in the *master.info file is immediately reset using any values specified in the corresponding startup options. This information includes values such as master host, master port, master user, and master password. If the slave SQL thread was in the middle of replicating temporary tables when it was stopped, and RESET SLAVE is issued, these replicated temporary tables are deleted on the slave. This statement was named FLUSH SLAVE before MySQL 3.23.26.    
26 POLYGON 2 Polygon(ls1,ls2,...) Constructs a WKB Polygon value from a number of WKB LineString arguments. If any argument does not represent the WKB of a LinearRing (that is, not a closed and simple LineString) the return value is NULL.    
27 MINUTE 14 MINUTE(time) Returns the minute for time, in the range 0 to 59. mysql> SELECT MINUTE('98-02-03 10:05:03'); -> 5  
28 DAY 14 DAY(date) DAY() is a synonym for DAYOFMONTH(). It is available as of MySQL 4.1.1.    
29 MID 23 MID(str,pos,len) MID(str,pos,len) is a synonym for SUBSTRING(str,pos,len).    
30 REPLACE INTO 6 REPLACE works exactly like INSERT, except that if an old record in the table has the same value as a new record for a PRIMARY KEY or a UNIQUE index, the old record is deleted before the new record is inserted. See also : [INSERT, ,INSERT]. Note that unless the table has a PRIMARY KEY or UNIQUE index, using a REPLACE statement makes no sense. It becomes equivalent to INSERT, because there is no index to be used to determine whether a new row duplicates another. Values for all columns are taken from the values specified in the REPLACE statement. Any missing columns are set to their default values, just as happens for INSERT. You can't refer to values from the current row and use them in the new row. If you use an assignment such as SET col_name = col_name + 1, the reference to the column name on the right hand side is treated as DEFAULT(col_name), so the assignment is equivalent to SET col_name = DEFAULT(col_name) + 1. To be able to use REPLACE, you must have INSERT and DELETE privileges for the table. REPLACE [LOW_PRIORITY | DELAYED] [INTO] tbl_name [(col_name,...)] VALUES ({expr | DEFAULT},...),(...),...  
31 UUID 21 UUID() Returns a Universal Unique Identifier (UUID) generated according to ``DCE 1.1: Remote Procedure Call'' (Appendix A) CAE (Common Applications Environment) Specifications published by The Open Group in October 1997 (Document Number C706). A UUID is designed as a number that is globally unique in space and time. Two calls to UUID() are expected to generate two different values, even if these calls are performed on two separate computers that are not connected to each other. A UUID is a 128-bit number represented by a string of five hexadecimal numbers in aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee format: --- The first three numbers are generated from a timestamp. --- The fourth number preserves temporal uniqueness in case the timestamp value loses monotonicity (for example, due to daylight saving time). --- The fifth number is an IEEE 802 node number that provides spatial uniqueness. A random number is substituted if the latter is not available (for example, because the host computer has no Ethernet card, or we do not know how to find the hardware address of an interface on your operating system). In this case, spatial uniqueness cannot be guaranteed. Nevertheless, a collision should have /very/ low probability. Currently, the MAC address of an interface is taken into account only on FreeBSD and Linux. On other operating systems, MySQL uses a randomly generated 48-bit number. mysql> SELECT UUID(); -> '6ccd780c-baba-1026-9564-0040f4311e29'  
32 LINESTRING 2 LineString(pt1,pt2,...) Constructs a WKB LineString value from a number of WKB Point arguments. If any argument is not a WKB Point, the return value is NULL. If the number of Point arguments is less than two, the return value is NULL.    
33 CONNECTION_ID 25 CONNECTION_ID() Returns the connection ID (thread ID) for the connection. Every connection has its own unique ID. mysql> SELECT CONNECTION_ID(); -> 23786  
34 DELETE 6 DELETE deletes rows from tbl_name that satisfy the condition given by where_definition, and returns the number of records deleted. If you issue a DELETE statement with no WHERE clause, all rows are deleted. A faster way to do this, when you don't want to know the number of deleted rows, is to use TRUNCATE TABLE. See also : [TRUNCATE, , TRUNCATE]. DELETE [LOW_PRIORITY] [QUICK] [IGNORE] FROM tbl_name [WHERE where_definition] [ORDER BY ...] [LIMIT row_count]  
35 ROUND 4 ROUND(X) ROUND(X,D) Returns the argument X, rounded to the nearest integer. With two arguments, returns X rounded to D decimals. D can be negative to round D digits left of the decimal point of the value X. mysql> SELECT ROUND(-1.23); -> -1 mysql> SELECT ROUND(-1.58); -> -2 mysql> SELECT ROUND(1.58); -> 2 mysql> SELECT ROUND(1.298, 1); -> 1.3 mysql> SELECT ROUND(1.298, 0); -> 1 mysql> SELECT ROUND(23.298, -1); -> 20  
36 NULLIF 9 NULLIF(expr1,expr2) Returns NULL if expr1 = expr2 is true, else returns expr1. This is the same as CASE WHEN expr1 = expr2 THEN NULL ELSE expr1 END. mysql> SELECT NULLIF(1,1); -> NULL mysql> SELECT NULLIF(1,2); -> 1  
37 STOP SLAVE 7 STOP SLAVE [thread_type [, thread_type] ... ] thread_type: IO_THREAD | SQL_THREAD Stops the slave threads. STOP SLAVE requires the SUPER privilege. Like START SLAVE, as of MySQL 4.0.2, this statement may be used with the IO_THREAD and SQL_THREAD options to name the thread or threads to stop.    
38 TIMEDIFF 14 TIMEDIFF(expr,expr2) TIMEDIFF() returns the time between the start time expr and the end time expr2. expr and expr2 are time or date-and-time expressions, but both must be of the same type. mysql> SELECT TIMEDIFF('2000:01:01 00:00:00', -> '2000:01:01 00:00:00.000001'); -> '-00:00:00.000001' mysql> SELECT TIMEDIFF('1997-12-31 23:59:59.000001', -> '1997-12-30 01:01:01.000002'); -> '46:58:57.999999'  
39 RELATED 11 Related(g1,g2,pattern_matrix) Returns 1 or 0 to indicate whether or not the spatial relationship specified by pattern_matrix exists between g1 and g2. Returns -1 if the arguments are NULL. The pattern matrix is a string. Its specification will be noted here if this function is implemented.    
40 LINEFROMTEXT 3 LineFromText(wkt[,srid]) LineStringFromText(wkt[,srid]) Constructs a LINESTRING value using its WKT representation and SRID.    
41 SHOW MASTER STATUS 6 SHOW MASTER STATUS Provides status information on the binary log files of the master.    
42 ADDTIME 14 ADDTIME(expr,expr2) ADDTIME() adds expr2 to expr and returns the result. expr is a time or datetime expression, and expr2 is a time expression. mysql> SELECT ADDTIME('1997-12-31 23:59:59.999999', -> '1 1:1:1.000002'); -> '1998-01-02 01:01:01.000001' mysql> SELECT ADDTIME('01:00:00.999999', '02:00:00.999998'); -> '03:00:01.999997'  
43 SPATIAL 24 MySQL can create spatial indexes using syntax similar to that for creating regular indexes, but extended with the SPATIAL keyword. Spatial columns that are indexed currently must be declared NOT NULL. The following examples demonstrate how to create spatial indexes. With CREATE TABLE: mysql> CREATE TABLE geom (g GEOMETRY NOT NULL, SPATIAL INDEX(g)); With ALTER TABLE: mysql> ALTER TABLE geom ADD SPATIAL INDEX(g); With CREATE INDEX: mysql> CREATE SPATIAL INDEX sp_index ON geom (g); To drop spatial indexes, use ALTER TABLE or DROP INDEX: With ALTER TABLE: mysql> ALTER TABLE geom DROP INDEX g; With DROP INDEX: mysql> DROP INDEX sp_index ON geom; Example: Suppose that a table geom contains more than 32,000 geometries, which are stored in the column g of type GEOMETRY. The table also has an AUTO_INCREMENT column fid for storing object ID values.    
44 TIMESTAMPDIFF 14 TIMESTAMPDIFF(interval,datetime_expr1,datetime_expr2) Returns the integer difference between the date or datetime expressions datetime_expr1 and datetime_expr2. The unit for the result is given by the interval argument. The legal values for interval are the same as those listed in the description of the TIMESTAMPADD() function.    
45 UPPER 23 UPPER(str) Returns the string str with all characters changed to uppercase according to the current character set mapping (the default is ISO-8859-1 Latin1). mysql> SELECT UPPER('Hej'); -> 'HEJ'  
46 FROM_UNIXTIME 14 FROM_UNIXTIME(unix_timestamp) FROM_UNIXTIME(unix_timestamp,format) Returns a representation of the unix_timestamp argument as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT FROM_UNIXTIME(875996580); -> '1997-10-04 22:23:00' mysql> SELECT FROM_UNIXTIME(875996580) + 0; -> 19971004222300 If format is given, the result is formatted according to the format string. format may contain the same specifiers as those listed in the entry for the DATE_FORMAT() function. mysql> SELECT FROM_UNIXTIME(UNIX_TIMESTAMP(), -> '%Y %D %M %h:%i:%s %x'); -> '2003 6th August 06:22:58 2003'  
47 MEDIUMBLOB 1 MEDIUMBLOB A BLOB column with a maximum length of 16,777,215 (2^24 - 1) bytes.    
48 IFNULL 9 IFNULL(expr1,expr2) If expr1 is not NULL, IFNULL() returns expr1, else it returns expr2. IFNULL() returns a numeric or string value, depending on the context in which it is used. mysql> SELECT IFNULL(1,0); -> 1 mysql> SELECT IFNULL(NULL,10); -> 10 mysql> SELECT IFNULL(1/0,10); -> 10 mysql> SELECT IFNULL(1/0,'yes'); -> 'yes'  
49 LEAST 26 LEAST(value1,value2,...) With two or more arguments, returns the smallest (minimum-valued) argument. The arguments are compared using the following rules. --- If the return value is used in an INTEGER context or all arguments are integer-valued, they are compared as integers. --- If the return value is used in a REAL context or all arguments are real-valued, they are compared as reals. --- If any argument is a case-sensitive string, the arguments are compared as case-sensitive strings. --- In other cases, the arguments are compared as case-insensitive strings. mysql> SELECT LEAST(2,0); -> 0 mysql> SELECT LEAST(34.0,3.0,5.0,767.0); -> 3.0 mysql> SELECT LEAST('B','A','C'); -> 'A'  
50 = 26 = Equal: mysql> SELECT 1 = 0; -> 0 mysql> SELECT '0' = 0; -> 1 mysql> SELECT '0.0' = 0; -> 1 mysql> SELECT '0.01' = 0; -> 0 mysql> SELECT '.01' = 0.01; -> 1  
51 REVERSE 23 REVERSE(str) Returns the string str with the order of the characters reversed. mysql> SELECT REVERSE('abc'); -> 'cba'  
52 ISNULL 26 ISNULL(expr) If expr is NULL, ISNULL() returns 1, otherwise it returns 0. mysql> SELECT ISNULL(1+1); -> 0 mysql> SELECT ISNULL(1/0); -> 1  
53 BINARY 1 BINARY(M) The BINARY type is similar to the CHAR type, but stores binary byte strings rather than non-binary character strings. This type was added in MySQL 4.1.2.    
54 BOUNDARY 19 Boundary(g) Returns a geometry that is the closure of the combinatorial boundary of the geometry value g.    
55 CREATE USER 7 The CREATE USER statement creates new MySQL accounts. To use it, you must have the global CREATE USER privilege or the INSERT privilege for the mysql database. For each account, CREATE USER creates a new record in the mysql.user table that has no privileges. An error occurs if the account already exists. The account can be given a password with the optional IDENTIFIED BY clause. The user value and the password are given the same way as for the GRANT statement. In particular, to specify the password in plain text, omit the PASSWORD keyword. To specify the password as the hashed value as returned by the PASSWORD() function, include the keyword PASSWORD. See also : [GRANT, , GRANT]. The CREATE USER statement was added in MySQL 5.0.2. @subsubsection DROP USER Syntax DROP USER user [, user] ... The DROP USER statement deletes one or more MySQL accounts. To use it, you must have the global CREATE USER privilege or the DELETE privilege for the mysql database. Each account is named using the same format as for GRANT or REVOKE; for example, 'jeffrey'@@'localhost'. The user and host parts of the account name correspond to the User and Host column values of the user table record for the account. DROP USER was added in MySQL 4.1.1 and originally removed only accounts that have no privileges. In MySQL 5.0.2, it was modified to also remove account privileges. This means that the procedure for removing an account depends on your version of MySQL. As of MySQL 5.0.2, remove an account and its privileges as follows: DROP USER user; The statement removes privilege records for the account from all grant tables. From MySQL 4.1.1 to 5.0.1, DROP USER deletes only MySQL accounts that don't have any privileges. In these MySQL versions, it serves only to remove each account record from the user table. To remove a MySQL account, you should use the following procedure, performing the steps in the order shown: @enumerate --- Use SHOW GRANTS to determine what privileges the account has. See also : [SHOW GRANTS, , SHOW GRANTS]. --- Use REVOKE to revoke the privileges displayed by SHOW GRANTS. This removes records for the account from all the grant tables except the user table, and revokes any global privileges listed in the user table. See also : [GRANT, , GRANT]. --- Delete the account by using DROP USER to remove the user table record. @end enumerate DROP USER does not automatically close any open user sessions. Rather, in the event that a user with an open session is dropped, the command does not take effect until that user's session is closed. Once the session is closed, the user is dropped, and that user's next attempt to log in will fail. This is by design. Before MySQL 4.1.1, DROP USER is not available. You should first revoke the account privileges as just described. Then delete the user table record and flush the grant tables like this: mysql> DELETE FROM mysql.user -> WHERE User='user_name' and Host='host_name'; mysql> FLUSH PRIVILEGES; @subsubsection GRANT and REVOKE Syntax GRANT priv_type [(column_list)] [, priv_type [(column_list)]] ... ON [object_type] {tbl_name | * | *.* | db_name.*} TO user [IDENTIFIED BY [PASSWORD] 'password'] [, user [IDENTIFIED BY [PASSWORD] 'password']] ... [REQUIRE NONE | [{SSL| X509}] [CIPHER 'cipher' [AND]] [ISSUER 'issuer' [AND]] [SUBJECT 'subject']] [WITH with_option [with_option] ...] object_type = TABLE | FUNCTION | PROCEDURE with_option = GRANT OPTION | MAX_QUERIES_PER_HOUR count | MAX_UPDATES_PER_HOUR count | MAX_CONNECTIONS_PER_HOUR count | MAX_USER_CONNECTIONS count REVOKE priv_type [(column_list)] [, priv_type [(column_list)]] ... ON [object_type] {tbl_name | * | *.* | db_name.*} FROM user [, user] ... REVOKE ALL PRIVILEGES, GRANT OPTION FROM user [, user] ... The GRANT and REVOKE statements allow system administrators to create MySQL user accounts and to grant rights to and revoke them from accounts. GRANT and REVOKE are implemented in MySQL 3.22.11 or later. For earlier MySQL versions, these statements do nothing. MySQL account information is stored in the tables of the mysql database. This database and the access control system are discussed extensively in [MySQL Database Administration], which you should consult for additional details. If the grant tables contain privilege records that contain mixed-case database or table names and the lower_case_table_names system variable is set, REVOKE cannot be used to revoke the privileges. It will be necessary to manipulate the grant tables directly. (GRANT will not create such records when lower_case_table_names is set, but such records might have been created prior to setting the variable.) Privileges can be granted at several levels: Global level Global privileges apply to all databases on a given server. These privileges are stored in the mysql.user table. GRANT ALL ON *.* and REVOKE ALL ON *.* grant and revoke only global privileges. Database level Database privileges apply to all objects in a given database. These privileges are stored in the mysql.db and mysql.host tables. GRANT ALL ON db_name.* and REVOKE ALL ON db_name.* grant and revoke only database privileges. Table level Table privileges apply to all columns in a given table. These privileges are stored in the mysql.tables_priv table. GRANT ALL ON db_name.tbl_name and REVOKE ALL ON db_name.tbl_name grant and revoke only table privileges. Column level Column privileges apply to single columns in a given table. These privileges are stored in the mysql.columns_priv table. When using REVOKE, you must specify the same columns that were granted. Routine level The CREATE ROUTINE, ALTER ROUTINE, EXECUTE, and GRANT privileges apply to stored routines. They can be granted at the global and database levels. Also, except for CREATE ROUTINE, these privileges can be granted at the routine level for individual routines and are stored in the mysql.procs_priv table. The object_type clause was added in MySQL 5.0.6. It should be specified as TABLE, FUNCTION, or PROCEDURE when the following object is a table, a stored function, or a stored procedure. To use this clause when upgrading from a version of MySQL older than 5.0.6, you must upgrade your grant tables. See also : [Upgrading-grant-tables]. CREATE USER user [IDENTIFIED BY [PASSWORD] 'password'] [, user [IDENTIFIED BY [PASSWORD] 'password']] ...  
56 POINT 2 Point(x,y) Constructs a WKB Point using its coordinates.    
57 CURRENT_USER 25 CURRENT_USER() Returns the username and hostname combination that the current session was authenticated as. This value corresponds to the MySQL account that determines your access privileges. It can be different from the value of USER(). mysql> SELECT USER(); -> 'davida@localhost' mysql> SELECT * FROM mysql.user; ERROR 1044: Access denied for user ''@'localhost' to database 'mysql' mysql> SELECT CURRENT_USER(); -> '@localhost'  
58 LCASE 23 LCASE(str) LCASE() is a synonym for LOWER().    
59 <= 26 <= Less than or equal: mysql> SELECT 0.1 <= 2; -> 1  
60 UPDATE 6 The UPDATE statement updates columns in existing table rows with new values. The SET clause indicates which columns to modify and the values they should be given. The WHERE clause, if given, specifies which rows should be updated. Otherwise, all rows are updated. If the ORDER BY clause is specified, the rows are updated in the order that is specified. The LIMIT clause places a limit on the number of rows that can be updated. The UPDATE statement supports the following modifiers: --- If you specify the LOW_PRIORITY keyword, execution of the UPDATE is delayed until no other clients are reading from the table. --- If you specify the IGNORE keyword, the update statement does not abort even if errors occur during the update. Rows for which duplicate-key conflicts occur are not updated. Rows for which columns are updated to values that would cause data conversion errors are updated to the closet valid values instead. UPDATE [LOW_PRIORITY] [IGNORE] tbl_name SET col_name1=expr1 [, col_name2=expr2 ...] [WHERE where_definition] [ORDER BY ...] [LIMIT row_count]  
61 DROP INDEX 28 DROP INDEX drops the index named index_name from the table tbl_name. In MySQL 3.22 or later, DROP INDEX is mapped to an ALTER TABLE statement to drop the index. See also : [ALTER TABLE, , ALTER TABLE]. DROP INDEX doesn't do anything prior to MySQL 3.22. DROP INDEX index_name ON tbl_name  
62 MATCH AGAINST 23 As of MySQL 3.23.23, MySQL has support for full-text indexing and searching. A full-text index in MySQL is an index of type FULLTEXT. FULLTEXT indexes are used with MyISAM tables only and can be created from CHAR, VARCHAR, or TEXT columns at CREATE TABLE time or added later with ALTER TABLE or CREATE INDEX. For large datasets, it is much faster to load your data into a table that has no FULLTEXT index, then create the index with ALTER TABLE (or CREATE INDEX). Loading data into a table that has an existing FULLTEXT index could be significantly slower. mysql> SELECT id, body, MATCH (title,body) AGAINST -> ('Security implications of running MySQL as root') AS score -> FROM articles WHERE MATCH (title,body) AGAINST -> ('Security implications of running MySQL as root'); +----+-------------------------------------+-----------------+ | id | body | score | +----+-------------------------------------+-----------------+ | 4 | 1. Never run mysqld as root. 2. ... | 1.5219271183014 | | 6 | When configured properly, MySQL ... | 1.3114095926285 | +----+-------------------------------------+-----------------+ 2 rows in set (0.00 sec)  
63 ABS 4 ABS(X) Returns the absolute value of X. mysql> SELECT ABS(2); -> 2 mysql> SELECT ABS(-32); -> 32  
64 POLYFROMWKB 13 PolyFromWKB(wkb[,srid]) PolygonFromWKB(wkb[,srid]) Constructs a POLYGON value using its WKB representation and SRID.    
65 NOT LIKE 23 expr NOT LIKE pat [ESCAPE 'escape-char'] This is the same as NOT (expr LIKE pat [ESCAPE 'escape-char']).    
66 SPACE 23 SPACE(N) Returns a string consisting of N space characters. mysql> SELECT SPACE(6); -> ' '  
67 MBR DEFINITION 8 Every geometry occupies some position in space. The exterior of a geometry is all space not occupied by the geometry. The interior is the space occupied by the geometry. The boundary is the interface between the geometry's interior and exterior. --- Its MBR (Minimum Bounding Rectangle), or Envelope. This is the bounding geometry, formed by the minimum and maximum (X,Y) coordinates: ((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))  
68 GEOMETRYCOLLECTION 2 GeometryCollection(g1,g2,...) Constructs a WKB GeometryCollection. If any argument is not a well-formed WKB representation of a geometry, the return value is NULL.    
69 * 4 * Multiplication: mysql> SELECT 3*5; -> 15 mysql> SELECT 18014398509481984*18014398509481984.0; -> 324518553658426726783156020576256.0 mysql> SELECT 18014398509481984*18014398509481984; -> 0  
70 TIMESTAMP 1 TIMESTAMP[(M)] A timestamp. The range is '1970-01-01 00:00:00' to partway through the year 2037. A TIMESTAMP column is useful for recording the date and time of an INSERT or UPDATE operation. The first TIMESTAMP column in a table is automatically set to the date and time of the most recent operation if you don't assign it a value yourself. You can also set any TIMESTAMP column to the current date and time by assigning it a NULL value. From MySQL 4.1 on, TIMESTAMP is returned as a string with the format 'YYYY-MM-DD HH:MM:SS'. If you want to obtain the value as a number, you should add +0 to the timestamp column. Different timestamp display widths are not supported. In MySQL 4.0 and earlier, TIMESTAMP values are displayed in YYYYMMDDHHMMSS, YYMMDDHHMMSS, YYYYMMDD, or YYMMDD format, depending on whether M is 14 (or missing), 12, 8, or 6, but allows you to assign values to TIMESTAMP columns using either strings or numbers. The M argument affects only how a TIMESTAMP column is displayed, not storage. Its values always are stored using four bytes each. From MySQL 4.0.12, the --new option can be used to make the server behave as in MySQL 4.1. Note that TIMESTAMP(M) columns where M is 8 or 14 are reported to be numbers, whereas other TIMESTAMP(M) columns are reported to be strings. This is just to ensure that you can reliably dump and restore the table with these types.    
71 DES_DECRYPT 17 DES_DECRYPT(crypt_str[,key_str]) Decrypts a string encrypted with DES_ENCRYPT(). On error, this function returns NULL. Note that this function works only if MySQL has been configured with SSL support. See also : [Secure connections]. If no key_str argument is given, DES_DECRYPT() examines the first byte of the encrypted string to determine the DES key number that was used to encrypt the original string, and then reads the key from the DES key file to decrypt the message. For this to work, the user must have the SUPER privilege. The key file can be specified with the --des-key-file server option. If you pass this function a key_str argument, that string is used as the key for decrypting the message. If the crypt_str argument doesn't look like an encrypted string, MySQL returns the given crypt_str.    
72 CHECKSUM 7 Reports a table checksum. If QUICK is specified, the live table checksum is reported if it is available, or NULL otherwise. This is very fast. A live checksum is enabled by specifying the CHECKSUM=1 table option, currently supported only for MyISAM tables. See also : [CREATE TABLE, , CREATE TABLE]. In EXTENDED mode the whole table is read row by row and the checksum is calculated. This can be very slow for large tables. By default, if neither QUICK nor EXTENDED is specified, MySQL returns a live checksum if the table storage engine supports it and scans the table otherwise. CHECKSUM TABLE returns NULL for non-existent tables. As of MySQL 5.0.3, a warning is generated for this condition. This statement is implemented in MySQL 4.1.1. @subsubsection OPTIMIZE TABLE Syntax OPTIMIZE [LOCAL | NO_WRITE_TO_BINLOG] TABLE tbl_name [, tbl_name] ... OPTIMIZE TABLE should be used if you have deleted a large part of a table or if you have made many changes to a table with variable-length rows (tables that have VARCHAR, BLOB, or TEXT columns). Deleted records are maintained in a linked list and subsequent INSERT operations reuse old record positions. You can use OPTIMIZE TABLE to reclaim the unused space and to defragment the data file. CHECKSUM TABLE tbl_name [, tbl_name] ... [ QUICK | EXTENDED ]  
73 ENDPOINT 18 EndPoint(ls) Returns the Point that is the end point of the LineString value ls. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT AsText(EndPoint(GeomFromText(@ls))); +-------------------------------------+ | AsText(EndPoint(GeomFromText(@ls))) | +-------------------------------------+ | POINT(3 3) | +-------------------------------------+  
74 CACHE INDEX 6 The CACHE INDEX statement assigns table indexes to a specific key cache. It is used only for MyISAM tables. The following statement assigns indexes from the tables t1, t2, and t3 to the key cache named hot_cache: mysql> CACHE INDEX t1, t2, t3 IN hot_cache; +---------+--------------------+----------+----------+ | Table | Op | Msg_type | Msg_text | +---------+--------------------+----------+----------+ | test.t1 | assign_to_keycache | status | OK | | test.t2 | assign_to_keycache | status | OK | | test.t3 | assign_to_keycache | status | OK | +---------+--------------------+----------+----------+ CACHE INDEX tbl_index_list [, tbl_index_list] ... IN key_cache_name tbl_index_list: tbl_name [[INDEX|KEY] (index_name[, index_name] ...)]  
75 COMPRESS 23 COMPRESS(string_to_compress) Compresses a string. This function requires MySQL to have been compiled with a compression library such as zlib. Otherwise, the return value is always NULL. The compressed string can be uncompressed with UNCOMPRESS(). mysql> SELECT LENGTH(COMPRESS(REPEAT('a',1000))); -> 21 mysql> SELECT LENGTH(COMPRESS('')); -> 0 mysql> SELECT LENGTH(COMPRESS('a')); -> 13 mysql> SELECT LENGTH(COMPRESS(REPEAT('a',16))); -> 15  
76 COUNT 12 COUNT(expr) Returns a count of the number of non-NULL values in the rows retrieved by a SELECT statement. mysql> SELECT student.student_name,COUNT(*) -> FROM student,course -> WHERE student.student_id=course.student_id -> GROUP BY student_name;  
77 INSERT 23 INSERT(str,pos,len,newstr) Returns the string str, with the substring beginning at position pos and len characters long replaced by the string newstr. Returns the original string if pos is not within the length of the string. Replaces the rest of the string from position pos is len is not within the length of the rest of the string. Returns NULL if any argument is null. mysql> SELECT INSERT('Quadratic', 3, 4, 'What'); -> 'QuWhattic' mysql> SELECT INSERT('Quadratic', -1, 4, 'What'); -> 'Quadratic' mysql> SELECT INSERT('Quadratic', 3, 100, 'What'); -> 'QuWhat'  
78 HANDLER 6 The HANDLER statement provides direct access to table storage engine interfaces. It is available for MyISAM tables as MySQL 4.0.0 and InnoDB tables as of MySQL 4.0.3. HANDLER tbl_name OPEN [ AS alias ] HANDLER tbl_name READ index_name { = | >= | <= | < } (value1,value2,...) [ WHERE where_condition ] [LIMIT ... ] HANDLER tbl_name READ index_name { FIRST | NEXT | PREV | LAST } [ WHERE where_condition ] [LIMIT ... ] HANDLER tbl_name READ { FIRST | NEXT } [ WHERE where_condition ] [LIMIT ... ] HANDLER tbl_name CLOSE  
79 MLINEFROMTEXT 3 MLineFromText(wkt[,srid]) MultiLineStringFromText(wkt[,srid]) Constructs a MULTILINESTRING value using its WKT representation and SRID.    
80 GEOMCOLLFROMWKB 13 GeomCollFromWKB(wkb[,srid]) GeometryCollectionFromWKB(wkb[,srid]) Constructs a GEOMETRYCOLLECTION value using its WKB representation and SRID.    
81 RENAME TABLE 28 RENAME TABLE tbl_name TO new_tbl_name [, tbl_name2 TO new_tbl_name2] ... This statement renames one or more tables. It was added in MySQL 3.23.23. The rename operation is done atomically, which means that no other thread can access any of the tables while the rename is running. For example, if you have an existing table old_table, you can create another table new_table that has the same structure but is empty, and then replace the existing table with the empty one as follows: CREATE TABLE new_table (...); RENAME TABLE old_table TO backup_table, new_table TO old_table;  
82 BOOLEAN 1 BOOL BOOLEAN These are synonyms for TINYINT(1). The BOOLEAN synonym was added in MySQL 4.1.0. A value of zero is considered false. Non-zero values are considered true. In the future, full boolean type handling will be introduced in accordance with standard SQL.    
83 DEFAULT 21 DEFAULT(col_name) Returns the default value for a table column. Starting from MySQL 5.0.2, you get an error if the column doesn't have a default value. mysql> UPDATE t SET i = DEFAULT(i)+1 WHERE id < 100;  
84 TINYTEXT 1 TINYTEXT A TEXT column with a maximum length of 255 (2^8 - 1) characters.    
85 DECODE 17 DECODE(crypt_str,pass_str) Decrypts the encrypted string crypt_str using pass_str as the password. crypt_str should be a string returned from ENCODE().    
86 <=> 26 <=> NULL-safe equal. This operator performs an equality comparison like the = operator, but returns 1 rather than NULL if both operands are NULL, and 0 rather than NULL if one operand is NULL. mysql> SELECT 1 <=> 1, NULL <=> NULL, 1 <=> NULL; -> 1, 1, 0 mysql> SELECT 1 = 1, NULL = NULL, 1 = NULL; -> 1, NULL, NULL  
87 LOAD DATA FROM MASTER 6 LOAD DATA FROM MASTER Takes a snapshot of the master and copies it to the slave. It updates the values of MASTER_LOG_FILE and MASTER_LOG_POS so that the slave starts replicating from the correct position. Any table and database exclusion rules specified with the --replicate-*-do-* and --replicate-*-ignore-* options are honored. --replicate-rewrite-db is /not/ taken into account (because one user could, with this option, set up a non-unique mapping such as --replicate-rewrite-db=db1->db3 and --replicate-rewrite-db=db2->db3, which would confuse the slave when it loads the master's tables). Use of this statement is subject to the following conditions: --- It works only with MyISAM tables. Attempting to load a non-MyISAM table results in the error: ERROR 1189 (08S01): Net error reading from master --- It acquires a global read lock on the master while taking the snapshot, which prevents updates on the master during the load operation. In the future, it is planned to make this statement work with InnoDB tables and to remove the need for a global read lock by using non-blocking online backup. If you are loading big tables, you might have to increase the values of net_read_timeout and net_write_timeout on both your master and slave servers. See also : [Server system variables]. Note that LOAD DATA FROM MASTER does /not/ copy any tables from the mysql database. This makes it easy to have different users and privileges on the master and the slave. The LOAD DATA FROM MASTER statement requires the replication account that is used to connect to the master to have the RELOAD and SUPER privileges on the master and the SELECT privilege for all master tables you want to load. All master tables for which the user does not have the SELECT privilege are ignored by LOAD DATA FROM MASTER. This is because the master hides them from the user: LOAD DATA FROM MASTER calls SHOW DATABASES to know the master databases to load, but SHOW DATABASES returns only databases for which the user has some privilege. See [SHOW DATABASES, , SHOW DATABASES]. On the slave's side, the user that issues LOAD DATA FROM MASTER should have grants to drop and create the databases and tables that are copied.    
88 RESET 6 The RESET statement is used to clear the state of various server operations. It also acts as a stronger version of the FLUSH statement. See also : [FLUSH, , FLUSH]. RESET reset_option [, reset_option] ...  
89 GET_LOCK 21 GET_LOCK(str,timeout) Tries to obtain a lock with a name given by the string str, with a timeout of timeout seconds. Returns 1 if the lock was obtained successfully, 0 if the attempt timed out (for example, because another client has previously locked the name), or NULL if an error occurred (such as running out of memory or the thread was killed with mysqladmin kill). If you have a lock obtained with GET_LOCK(), it is released when you execute RELEASE_LOCK(), execute a new GET_LOCK(), or your connection terminates (either normally or abnormally). This function can be used to implement application locks or to simulate record locks. Names are locked on a server-wide basis. If a name has been locked by one client, GET_LOCK() blocks any request by another client for a lock with the same name. This allows clients that agree on a given lock name to use the name to perform cooperative advisory locking. mysql> SELECT GET_LOCK('lock1',10); -> 1 mysql> SELECT IS_FREE_LOCK('lock2'); -> 1 mysql> SELECT GET_LOCK('lock2',10); -> 1 mysql> SELECT RELEASE_LOCK('lock2'); -> 1 mysql> SELECT RELEASE_LOCK('lock1'); -> NULL  
90 UCASE 23 UCASE(str) UCASE() is a synonym for UPPER().    
91 MPOLYFROMWKB 13 MPolyFromWKB(wkb[,srid]) MultiPolygonFromWKB(wkb[,srid]) Constructs a MULTIPOLYGON value using its WKB representation and SRID.    
92 DO 6 DO executes the expressions but doesn't return any results. This is shorthand for SELECT expr, ..., but has the advantage that it's slightly faster when you don't care about the result. DO is useful mainly with functions that have side effects, such as RELEASE_LOCK(). DO expr [, expr] ...  
93 CURTIME 14 CURTIME() Returns the current time as a value in 'HH:MM:SS' or HHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT CURTIME(); -> '23:50:26' mysql> SELECT CURTIME() + 0; -> 235026  
94 BIGINT 1 BIGINT[(M)] [UNSIGNED] [ZEROFILL] A large integer. The signed range is -9223372036854775808 to 9223372036854775807. The unsigned range is 0 to 18446744073709551615.    
95 CHAR_LENGTH 23 CHAR_LENGTH(str) Returns the length of the string str, measured in characters. A multi-byte character counts as a single character. This means that for a string containing five two-byte characters, LENGTH() returns 10, whereas CHAR_LENGTH() returns 5.    
96 SET 6 SET sets different types of variables that affect the operation of the server or your client. It can be used to assign values to user variables or system variables. SET variable_assignment [, variable_assignment] ... variable_assignment: user_var_name = expr | [GLOBAL | SESSION] system_var_name = expr | @@[global. | session.]system_var_name = expr  
97 DATE 1 A date. The supported range is '1000-01-01' to '9999-12-31'. MySQL displays DATE values in 'YYYY-MM-DD' format, but allows you to assign values to DATE columns using either strings or numbers.    
98 CONV 23 CONV(N,from_base,to_base) Converts numbers between different number bases. Returns a string representation of the number N, converted from base from_base to base to_base. Returns NULL if any argument is NULL. The argument N is interpreted as an integer, but may be specified as an integer or a string. The minimum base is 2 and the maximum base is 36. If to_base is a negative number, N is regarded as a signed number. Otherwise, N is treated as unsigned. CONV() works with 64-bit precision. mysql> SELECT CONV('a',16,2); -> '1010' mysql> SELECT CONV('6E',18,8); -> '172' mysql> SELECT CONV(-17,10,-18); -> '-H' mysql> SELECT CONV(10+'10'+'10'+0xa,10,10); -> '40'  
99 EXTRACT 14 EXTRACT(type FROM date) The EXTRACT() function uses the same kinds of interval type specifiers as DATE_ADD() or DATE_SUB(), but extracts parts from the date rather than performing date arithmetic. mysql> SELECT EXTRACT(YEAR FROM '1999-07-02'); -> 1999 mysql> SELECT EXTRACT(YEAR_MONTH FROM '1999-07-02 01:02:03'); -> 199907 mysql> SELECT EXTRACT(DAY_MINUTE FROM '1999-07-02 01:02:03'); -> 20102 mysql> SELECT EXTRACT(MICROSECOND -> FROM '2003-01-02 10:30:00.00123'); -> 123  
100 ENCRYPT 17 ENCRYPT(str[,salt]) Encrypt str using the Unix crypt() system call. The salt argument should be a string with two characters. (As of MySQL 3.22.16, salt may be longer than two characters.) If no salt argument is given, a random value is used. mysql> SELECT ENCRYPT('hello'); -> 'VxuFAJXVARROc'  
101 OLD_PASSWORD 17 OLD_PASSWORD(str) OLD_PASSWORD() is available as of MySQL 4.1, when the implementation of PASSWORD() was changed to improve security. OLD_PASSWORD() returns the value of the pre-4.1 implementation of PASSWORD(). [Password hashing]. PASSWORD(str) Calculates and returns a password string from the plaintext password str, or NULL if the argument was NULL. This is the function that is used for encrypting MySQL passwords for storage in the Password column of the user grant table.    
102 FORMAT 21 FORMAT(X,D) Formats the number X to a format like '#,###,###.##', rounded to D decimals, and returns the result as a string. If D is 0, the result has no decimal point or fractional part. mysql> SELECT FORMAT(12332.123456, 4); -> '12,332.1235' mysql> SELECT FORMAT(12332.1,4); -> '12,332.1000' mysql> SELECT FORMAT(12332.2,0); -> '12,332'  
103 || 20 OR || Logical OR. When both operands are non-NULL, the result is 1 if any operand is non-zero, and 0 otherwise. With a NULL operand, the result is 1 if the other operand is non-zero, and NULL otherwise. If both operands are NULL, the result is NULL. mysql> SELECT 1 || 1; -> 1 mysql> SELECT 1 || 0; -> 1 mysql> SELECT 0 || 0; -> 0 mysql> SELECT 0 || NULL; -> NULL mysql> SELECT 1 || NULL; -> 1  
104 CASE 9 CASE value WHEN [compare-value] THEN result [WHEN [compare-value] THEN result ...] [ELSE result] END CASE WHEN [condition] THEN result [WHEN [condition] THEN result ...] [ELSE result] END The first version returns the result where value=compare-value. The second version returns the result for the first condition that is true. If there was no matching result value, the result after ELSE is returned, or NULL if there is no ELSE part. mysql> SELECT CASE 1 WHEN 1 THEN 'one' -> WHEN 2 THEN 'two' ELSE 'more' END; -> 'one' mysql> SELECT CASE WHEN 1>0 THEN 'true' ELSE 'false' END; -> 'true' mysql> SELECT CASE BINARY 'B' -> WHEN 'a' THEN 1 WHEN 'b' THEN 2 END; -> NULL  
105 BIT_LENGTH 23 BIT_LENGTH(str) Returns the length of the string str in bits. mysql> SELECT BIT_LENGTH('text'); -> 32  
106 EXTERIORRING 0 ExteriorRing(poly) Returns the exterior ring of the Polygon value poly as a LineString. mysql> SET @poly = -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'; mysql> SELECT AsText(ExteriorRing(GeomFromText(@poly))); +-------------------------------------------+ | AsText(ExteriorRing(GeomFromText(@poly))) | +-------------------------------------------+ | LINESTRING(0 0,0 3,3 3,3 0,0 0) | +-------------------------------------------+  
107 GEOMFROMWKB 13 GeomFromWKB(wkb[,srid]) GeometryFromWKB(wkb[,srid]) Constructs a geometry value of any type using its WKB representation and SRID.    
108 SHOW SLAVE HOSTS 6 SHOW SLAVE HOSTS Displays a list of slaves currently registered with the master. Any slave not started with the --report-host=slave_name option is not visible in that list.    
109 START TRANSACTION 10 By default, MySQL runs with autocommit mode enabled. This means that as soon as you execute a statement that updates (modifies) a table, MySQL stores the update on disk. If you are using transaction-safe tables (like InnoDB or BDB), you can disable autocommit mode with the following statement: SET AUTOCOMMIT=0; After disabling autocommit mode by setting the AUTOCOMMIT variable to zero, you must use COMMIT to store your changes to disk or ROLLBACK if you want to ignore the changes you have made since the beginning of your transaction. If you want to disable autocommit mode for a single series of statements, you can use the START TRANSACTION statement: START TRANSACTION; SELECT @A:=SUM(salary) FROM table1 WHERE type=1; UPDATE table2 SET summary=@A WHERE type=1; COMMIT;  
110 BETWEEN AND 26 expr BETWEEN min AND max If expr is greater than or equal to min and expr is less than or equal to max, BETWEEN returns 1, otherwise it returns 0. This is equivalent to the expression (min <= expr AND expr <= max) if all the arguments are of the same type. Otherwise type conversion takes place according to the rules described at the beginning of this section, but applied to all the three arguments. Note: Before MySQL 4.0.5, arguments were converted to the type of expr instead. mysql> SELECT 1 BETWEEN 2 AND 3; -> 0 mysql> SELECT 'b' BETWEEN 'a' AND 'c'; -> 1 mysql> SELECT 2 BETWEEN 2 AND '3'; -> 1 mysql> SELECT 2 BETWEEN 2 AND 'x-3'; -> 0  
111 MULTIPOLYGON 2 MultiPolygon(poly1,poly2,...) Constructs a WKB MultiPolygon value from a set of WKB Polygon arguments. If any argument is not a WKB Polygon, the return value is NULL.    
112 TIME_FORMAT 14 TIME_FORMAT(time,format) This is used like the DATE_FORMAT() function, but the format string may contain only those format specifiers that handle hours, minutes, and seconds. Other specifiers produce a NULL value or 0.    
113 LEFT 23 LEFT(str,len) Returns the leftmost len characters from the string str. mysql> SELECT LEFT('foobarbar', 5); -> 'fooba'  
114 FLUSH QUERY CACHE 7 You can defragment the query cache to better utilize its memory with the FLUSH QUERY CACHE statement. The statement does not remove any queries from the cache. The RESET QUERY CACHE statement removes all query results from the query cache. The FLUSH TABLES statement also does this.    
115 RAND 4 RAND() RAND(N) Returns a random floating-point value in the range from 0 to 1.0. If an integer argument N is specified, it is used as the seed value (producing a repeatable sequence). mysql> SELECT RAND(); -> 0.9233482386203 mysql> SELECT RAND(20); -> 0.15888261251047 mysql> SELECT RAND(20); -> 0.15888261251047 mysql> SELECT RAND(); -> 0.63553050033332 mysql> SELECT RAND(); -> 0.70100469486881  
116 RPAD 23 RPAD(str,len,padstr) Returns the string str, right-padded with the string padstr to a length of len characters. If str is longer than len, the return value is shortened to len characters. mysql> SELECT RPAD('hi',5,'?'); -> 'hi???' mysql> SELECT RPAD('hi',1,'?'); -> 'h'  
117 INSERT INTO 6 INSERT inserts new rows into an existing table. The INSERT ... VALUES and INSERT ... SET forms of the statement insert rows based on explicitly specified values. The INSERT ... SELECT form inserts rows selected from another table or tables. The INSERT ... VALUES form with multiple value lists is supported in MySQL 3.22.5 or later. The INSERT ... SET syntax is supported in MySQL 3.22.10 or later. INSERT ... SELECT is discussed further in See also : [INSERT SELECT, , INSERT SELECT]. INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE] [INTO] tbl_name [(col_name,...)] VALUES ({expr | DEFAULT},...),(...),... [ ON DUPLICATE KEY UPDATE col_name=expr, ... ]  
118 RESTORE 7 RESTORE TABLE tbl_name [, tbl_name] ... FROM '/path/to/backup/directory' Restores the table or tables from a backup that was made with BACKUP TABLE. Existing tables are not overwritten; if you try to restore over an existing table, you get an error. Just as BACKUP TABLE, RESTORE TABLE currently works only for MyISAM tables. The directory should be specified as a full pathname. The backup for each table consists of its *.frm format file and *.MYD data file. The restore operation restores those files, then uses them to rebuild the *.MYI index file. Restoring takes longer than backing up due to the need to rebuild the indexes. The more indexes the table has, the longer it takes.    
119 CREATE DATABASE 28 CREATE DATABASE creates a database with the given name. To use CREATE DATABASE, you need the CREATE privilege on the database. CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name [create_specification [, create_specification] ...] create_specification: [DEFAULT] CHARACTER SET charset_name | [DEFAULT] COLLATE collation_name  
120 VAR_POP 12 VAR_POP(expr) Returns the population standard variance of expr. It considers rows as the whole population, not as a sample, so it has the number of rows as the denominator. This function was added in MySQL 5.0.3. Before 5.0.3, you can use VARIANCE(), which is equivalent but not standard SQL.    
121 ELT 23 ELT(N,str1,str2,str3,...) Returns str1 if N = 1, str2 if N = 2, and so on. Returns NULL if N is less than 1 or greater than the number of arguments. ELT() is the complement of FIELD(). mysql> SELECT ELT(1, 'ej', 'Heja', 'hej', 'foo'); -> 'ej' mysql> SELECT ELT(4, 'ej', 'Heja', 'hej', 'foo'); -> 'foo'  
122 ALTER VIEW 24 This statement changes the definition of an existing view. The syntax is similar to that for CREATE VIEW. See also : [CREATE VIEW, , CREATE VIEW]. This statement requires the CREATE VIEW and DELETE privileges for the view, and some privilege for each column referred to in the SELECT statement. ALTER [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}] VIEW view_name [(column_list)] AS select_statement [WITH [CASCADED | LOCAL] CHECK OPTION]  
123 ~ 27 ~ Invert all bits. mysql> SELECT 5 & ~1; -> 4  
124 CONCAT_WS 23 CONCAT_WS(separator,str1,str2,...) CONCAT_WS() stands for CONCAT With Separator and is a special form of CONCAT(). The first argument is the separator for the rest of the arguments. The separator is added between the strings to be concatenated. The separator can be a string as can the rest of the arguments. If the separator is NULL, the result is NULL. The function skips any NULL values after the separator argument. mysql> SELECT CONCAT_WS(',','First name','Second name','Last Name'); -> 'First name,Second name,Last Name' mysql> SELECT CONCAT_WS(',','First name',NULL,'Last Name'); -> 'First name,Last Name'  
125 ROW_COUNT 25 ROW_COUNT() ROW_COUNT() returns the number of rows updated, inserted, or deleted by the preceding statement. This is the same as the row count that the mysql client displays and the value from the mysql_affected_rows() C API function. mysql> INSERT INTO t VALUES(1),(2),(3); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> SELECT ROW_COUNT(); +-------------+ | ROW_COUNT() | +-------------+ | 3 | +-------------+ 1 row in set (0.00 sec) mysql> DELETE FROM t WHERE i IN(1,2); Query OK, 2 rows affected (0.00 sec) mysql> SELECT ROW_COUNT(); +-------------+ | ROW_COUNT() | +-------------+ | 2 | +-------------+ 1 row in set (0.00 sec)  
126 ASIN 4 ASIN(X) Returns the arc sine of X, that is, the value whose sine is X. Returns NULL if X is not in the range -1 to 1. mysql> SELECT ASIN(0.2); -> 0.201358 mysql> SELECT ASIN('foo'); -> 0.000000  
127 FUNCTION 22 A user-defined function (UDF) is a way to extend MySQL with a new function that works like a native (built-in) MySQL function such as ABS() or CONCAT(). function_name is the name that should be used in SQL statements to invoke the function. The RETURNS clause indicates the type of the function's return value. shared_library_name is the basename of the shared object file that contains the code that implements the function. The file must be located in a directory that is searched by your system's dynamic linker. To create a function, you must have the INSERT and privilege for the mysql database. To drop a function, you must have the DELETE privilege for the mysql database. This is because CREATE FUNCTION adds a row to the mysql.func system table that records the function's name, type, and shared library name, and DROP FUNCTION deletes the function's row from that table. If you do not have this table, you should run the mysql_fix_privilege_tables script to create it. See also : [Upgrading-grant-tables]. CREATE [AGGREGATE] FUNCTION function_name RETURNS {STRING|INTEGER|REAL} SONAME shared_library_name DROP FUNCTION function_name  
128 SIGN 4 SIGN(X) Returns the sign of the argument as -1, 0, or 1, depending on whether X is negative, zero, or positive. mysql> SELECT SIGN(-32); -> -1 mysql> SELECT SIGN(0); -> 0 mysql> SELECT SIGN(234); -> 1  
129 SEC_TO_TIME 14 SEC_TO_TIME(seconds) Returns the seconds argument, converted to hours, minutes, and seconds, as a value in 'HH:MM:SS' or HHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT SEC_TO_TIME(2378); -> '00:39:38' mysql> SELECT SEC_TO_TIME(2378) + 0; -> 3938  
130 YEAR TYPE 1 YEAR[(2|4)] A year in two-digit or four-digit format. The default is four-digit format. In four-digit format, the allowable values are 1901 to 2155, and 0000. In two-digit format, the allowable values are 70 to 69, representing years from 1970 to 2069. MySQL displays YEAR values in YYYY format, but allows you to assign values to YEAR columns using either strings or numbers. The YEAR type is unavailable prior to MySQL 3.22.    
131 FLOAT 1 FLOAT(p) [UNSIGNED] [ZEROFILL] A floating-point number. p represents the precision. It can be from 0 to 24 for a single-precision floating-point number and from 25 to 53 for a double-precision floating-point number. These types are like the FLOAT and DOUBLE types described immediately following. FLOAT(p) has the same range as the corresponding FLOAT and DOUBLE types, but the display width and number of decimals are undefined. As of MySQL 3.23, this is a true floating-point value. In earlier MySQL versions, FLOAT(p) always has two decimals. This syntax is provided for ODBC compatibility. Using FLOAT might give you some unexpected problems because all calculations in MySQL are done with double precision. See also : [No matching rows]. FLOAT[(M,D)] [UNSIGNED] [ZEROFILL] A small (single-precision) floating-point number. Allowable values are -3.402823466E+38 to -1.175494351E-38, 0, and 1.175494351E-38 to 3.402823466E+38. If UNSIGNED is specified, negative values are disallowed. M is the display width and D is the number of significant digits. FLOAT without arguments or FLOAT(p) (where p is in the range from 0 to 24) stands for a single-precision floating-point number.    
132 LOCATE 23 LOCATE(substr,str) LOCATE(substr,str,pos) The first syntax returns the position of the first occurrence of substring substr in string str. The second syntax returns the position of the first occurrence of substring substr in string str, starting at position pos. Returns 0 if substr is not in str.    
133 CHARSET 25 CHARSET(str) Returns the character set of the string argument. mysql> SELECT CHARSET('abc'); -> 'latin1' mysql> SELECT CHARSET(CONVERT('abc' USING utf8)); -> 'utf8' mysql> SELECT CHARSET(USER()); -> 'utf8'  
134 PURGE MASTER LOGS BEFORE TO 6 PURGE {MASTER | BINARY} LOGS TO 'log_name' PURGE {MASTER | BINARY} LOGS BEFORE 'date' Deletes all the binary logs listed in the log index that are strictly prior to the specified log or date. The logs also are removed from the list recorded in the log index file, so that the given log becomes the first.    
135 SUBDATE 14 SUBDATE(date,INTERVAL expr type) SUBDATE(expr,days) When invoked with the INTERVAL form of the second argument, SUBDATE() is a synonym for DATE_SUB(). For information on the INTERVAL argument, see the discussion for DATE_ADD(). mysql> SELECT DATE_SUB('1998-01-02', INTERVAL 31 DAY); -> '1997-12-02' mysql> SELECT SUBDATE('1998-01-02', INTERVAL 31 DAY); -> '1997-12-02' As of MySQL 4.1.1, the second syntax is allowed, where expr is a date or datetime expression and days is the number of days to be subtracted from expr. mysql> SELECT SUBDATE('1998-01-02 12:00:00', 31); -> '1997-12-02 12:00:00' Note that you can't use format "%X%V" to convert a year-week string to date as a year-week doesn't uniquely identify a year-month if the week crosses a month boundary. If you want to convert a year-week to a date you can do it by also specifying the week day: mysql> select str_to_date('200442 Monday', '%X%V %W'); -> 2004-10-18    
136 DAYOFYEAR 14 DAYOFYEAR(date) Returns the day of the year for date, in the range 1 to 366. mysql> SELECT DAYOFYEAR('1998-02-03'); -> 34  
137 % 4 MOD(N,M) N % M N MOD M Modulo operation. Returns the remainder of N divided by M. mysql> SELECT MOD(234, 10); -> 4 mysql> SELECT 253 % 7; -> 1 mysql> SELECT MOD(29,9); -> 2 mysql> SELECT 29 MOD 9; -> 2  
138 LONGTEXT 1 LONGTEXT A TEXT column with a maximum length of 4,294,967,295 or 4GB (2^32 - 1) characters. Up to MySQL 3.23, the client/server protocol and MyISAM tables had a limit of 16MB per communication packet / table row. From MySQL 4.0, the maximum allowed length of LONGTEXT columns depends on the configured maximum packet size in the client/server protocol and available memory.    
139 DISJOINT 11 Disjoint(g1,g2) Returns 1 or 0 to indicate whether or not g1 is spatially disjoint from (does not intersect) g2.    
140 KILL 6 Each connection to mysqld runs in a separate thread. You can see which threads are running with the SHOW PROCESSLIST statement and kill a thread with the KILL thread_id statement. As of MySQL 5.0.0, KILL allows the optional CONNECTION or QUERY modifiers: --- KILL CONNECTION is the same as KILL with no modifier: It terminates the connection associated with the given thread_id. --- KILL QUERY terminates the statement that the connection currently is executing, but leaves the connection intact. If you have the PROCESS privilege, you can see all threads. If you have the SUPER privilege, you can kill all threads and statements. Otherwise, you can see and kill only your own threads and statements. You can also use the mysqladmin processlist and mysqladmin kill commands to examine and kill threads. Note: You currently cannot use KILL with the Embedded MySQL Server library, because the embedded server merely runs inside the threads of the host application, it does not create connection threads of its own. KILL [CONNECTION | QUERY] thread_id  
141 ASTEXT 3 AsText(g) Converts a value in internal geometry format to its WKT representation and returns the string result. mysql> SELECT AsText(g) FROM geom; +-------------------------+ | AsText(p1) | +-------------------------+ | POINT(1 1) | | LINESTRING(0 0,1 1,2 2) | +-------------------------+  
142 LPAD 23 LPAD(str,len,padstr) Returns the string str, left-padded with the string padstr to a length of len characters. If str is longer than len, the return value is shortened to len characters. mysql> SELECT LPAD('hi',4,'??'); -> '??hi' mysql> SELECT LPAD('hi',1,'??'); -> 'h'  
143 OVERLAPS 11 Overlaps(g1,g2) Returns 1 or 0 to indicate whether or not g1 spatially overlaps g2. The term /spatially overlaps/ is used if two geometries intersect and their intersection results in a geometry of the same dimension but not equal to either of the given geometries.    
144 NUMGEOMETRIES 5 NumGeometries(gc) Returns the number of geometries in the GeometryCollection value gc. mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))'; mysql> SELECT NumGeometries(GeomFromText(@gc)); +----------------------------------+ | NumGeometries(GeomFromText(@gc)) | +----------------------------------+ | 2 | +----------------------------------+  
145 SET GLOBAL SQL_SLAVE_SKIP_COUNTER 7 SET GLOBAL SQL_SLAVE_SKIP_COUNTER = n Skip the next n events from the master. This is useful for recovering from replication stops caused by a statement. This statement is valid only when the slave thread is not running. Otherwise, it produces an error. Before MySQL 4.0, omit the GLOBAL keyword from the statement.    
146 MONTHNAME 14 MONTHNAME(date) Returns the full name of the month for date. mysql> SELECT MONTHNAME('1998-02-05'); -> 'February'  
147 MBREQUAL 8 MBREqual(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangles of the two geometries g1 and g2 are the same.    
148 CHANGE MASTER TO 6 CHANGE MASTER TO master_def [, master_def] ... master_def: MASTER_HOST = 'host_name' | MASTER_USER = 'user_name' | MASTER_PASSWORD = 'password' | MASTER_PORT = port_num | MASTER_CONNECT_RETRY = count | MASTER_LOG_FILE = 'master_log_name' | MASTER_LOG_POS = master_log_pos | RELAY_LOG_FILE = 'relay_log_name' | RELAY_LOG_POS = relay_log_pos | MASTER_SSL = {0|1} | MASTER_SSL_CA = 'ca_file_name' | MASTER_SSL_CAPATH = 'ca_directory_name' | MASTER_SSL_CERT = 'cert_file_name' | MASTER_SSL_KEY = 'key_file_name' | MASTER_SSL_CIPHER = 'cipher_list' Changes the parameters that the slave server uses for connecting to and communicating with the master server. MASTER_USER, MASTER_PASSWORD, MASTER_SSL, MASTER_SSL_CA, MASTER_SSL_CAPATH, MASTER_SSL_CERT, MASTER_SSL_KEY, and MASTER_SSL_CIPHER provide information for the slave about how to connect to its master. The relay log options (RELAY_LOG_FILE and RELAY_LOG_POS) are available beginning with MySQL 4.0. The SSL options (MASTER_SSL, MASTER_SSL_CA, MASTER_SSL_CAPATH, MASTER_SSL_CERT, MASTER_SSL_KEY, and MASTER_SSL_CIPHER) are available beginning with MySQL 4.1.1. You can change these options even on slaves that are compiled without SSL support. They are saved to the *master.info file, but are ignored until you use a server that has SSL support enabled. If you don't specify a given parameter, it keeps its old value, except as indicated in the following discussion. For example, if the password to connect to your MySQL master has changed, you just need to issue these statements to tell the slave about the new password: mysql> STOP SLAVE; -- if replication was running mysql> CHANGE MASTER TO MASTER_PASSWORD='new3cret'; mysql> START SLAVE; -- if you want to restart replication There is no need to specify the parameters that do not change (host, port, user, and so forth). MASTER_HOST and MASTER_PORT are the hostname (or IP address) of the master host and its TCP/IP port. Note that if MASTER_HOST is equal to localhost, then, like in other parts of MySQL, the port may be ignored (if Unix socket files can be used, for example). If you specify MASTER_HOST or MASTER_PORT, the slave assumes that the master server is different than before (even if you specify a host or port value that is the same as the current value.) In this case, the old values for the master binary log name and position are considered no longer applicable, so if you do not specify MASTER_LOG_FILE and MASTER_LOG_POS in the statement, MASTER_LOG_FILE='' and MASTER_LOG_POS=4 are silently appended to it. MASTER_LOG_FILE and MASTER_LOG_POS are the coordinates at which the slave I/O thread should begin reading from the master the next time the thread starts. If you specify either of them, you can't specify RELAY_LOG_FILE or RELAY_LOG_POS. If neither of MASTER_LOG_FILE or MASTER_LOG_POS are specified, the slave uses the last coordinates of the /slave SQL thread/ before CHANGE MASTER was issued. This ensures that replication has no discontinuity, even if the slave SQL thread was late compared to the slave I/O thread, when you just want to change, say, the password to use. This safe behavior was introduced starting from MySQL 4.0.17 and 4.1.1. (Before these versions, the coordinates used were the last coordinates of the slave I/O thread before CHANGE MASTER was issued. This caused the SQL thread to possibly lose some events from the master, thus breaking replication.) CHANGE MASTER /deletes all relay log files/ and starts a new one, unless you specify RELAY_LOG_FILE or RELAY_LOG_POS. In that case, relay logs are kept; as of MySQL 4.1.1 the relay_log_purge global variable is set silently to 0. CHANGE MASTER TO updates the contents of the *master.info and *relay-log.info files. CHANGE MASTER is useful for setting up a slave when you have the snapshot of the master and have recorded the log and the offset corresponding to it. After loading the snapshot into the slave, you can run CHANGE MASTER TO MASTER_LOG_FILE='log_name_on_master', MASTER_LOG_POS=log_offset_on_master on the slave. Examples: mysql> CHANGE MASTER TO -> MASTER_HOST='master2.mycompany.com', -> MASTER_USER='replication', -> MASTER_PASSWORD='bigs3cret', -> MASTER_PORT=3306, -> MASTER_LOG_FILE='master2-bin.001', -> MASTER_LOG_POS=4, -> MASTER_CONNECT_RETRY=10; mysql> CHANGE MASTER TO -> RELAY_LOG_FILE='slave-relay-bin.006', -> RELAY_LOG_POS=4025;    
149 DROP DATABASE 28 DROP DATABASE drops all tables in the database and deletes the database. Be /very/ careful with this statement! To use DROP DATABASE, you need the DROP privilege on the database. In MySQL 3.22 or later, you can use the keywords IF EXISTS to prevent an error from occurring if the database doesn't exist. DROP SCHEMA can be used as of MySQL 5.0.2. DROP {DATABASE | SCHEMA} [IF EXISTS] db_name  
150 TIMESTAMP FUNCTION 14 TIMESTAMP(expr) TIMESTAMP(expr,expr2) With one argument, returns the date or datetime expression expr as a datetime value. With two arguments, adds the time expression expr2 to the date or datetime expression expr and returns a datetime value. mysql> SELECT TIMESTAMP('2003-12-31'); -> '2003-12-31 00:00:00' mysql> SELECT TIMESTAMP('2003-12-31 12:00:00','12:00:00'); -> '2004-01-01 00:00:00'  
151 CHARACTER_LENGTH 23 CHARACTER_LENGTH(str) CHARACTER_LENGTH() is a synonym for CHAR_LENGTH().    
152 CREATE VIEW ALGORITHM MERGE TEMPTABLE WITH CHECK OPTION 24   CREATE [OR REPLACE] [ALGORITHM = {UNDEFINED | MERGE | TEMPTABLE}] VIEW view_name [(column_list)] AS select_statement [WITH [CASCADED | LOCAL] CHECK OPTION]  
153 TIMESTAMPDIFF FUNCTION 14   mysql> SELECT TIMESTAMPDIFF(MONTH,'2003-02-01','2003-05-01'); -> 3 mysql> SELECT TIMESTAMPDIFF(YEAR,'2002-05-01','2001-01-01'); -> -1  
154 CRC32 4 CRC32(expr) Computes a cyclic redundancy check value and returns a 32-bit unsigned value. The result is NULL if the argument is NULL. The argument is expected be a string and is treated as one if it is not. mysql> SELECT CRC32('MySQL'); -> 3259397556  
155 XOR 20 XOR Logical XOR. Returns NULL if either operand is NULL. For non-NULL operands, evaluates to 1 if an odd number of operands is non-zero, otherwise 0 is returned. mysql> SELECT 1 XOR 1; -> 0 mysql> SELECT 1 XOR 0; -> 1 mysql> SELECT 1 XOR NULL; -> NULL mysql> SELECT 1 XOR 1 XOR 1; -> 1  
156 STARTPOINT 18 StartPoint(ls) Returns the Point that is the start point of the LineString value ls. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT AsText(StartPoint(GeomFromText(@ls))); +---------------------------------------+ | AsText(StartPoint(GeomFromText(@ls))) | +---------------------------------------+ | POINT(1 1) | +---------------------------------------+  
157 MPOLYFROMTEXT 3 MPolyFromText(wkt[,srid]) MultiPolygonFromText(wkt[,srid]) Constructs a MULTIPOLYGON value using its WKT representation and SRID.    
158 MBRINTERSECTS 8 MBRIntersects(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangles of the two geometries g1 and g2 intersect.    
159 BIT_OR 12 BIT_OR(expr) Returns the bitwise OR of all bits in expr. The calculation is performed with 64-bit (BIGINT) precision.    
160 YEARWEEK 14 YEARWEEK(date) YEARWEEK(date,start) Returns year and week for a date. The start argument works exactly like the start argument to WEEK(). The year in the result may be different from the year in the date argument for the first and the last week of the year. mysql> SELECT YEARWEEK('1987-01-01'); -> 198653  
161 NOT BETWEEN 26 expr NOT BETWEEN min AND max This is the same as NOT (expr BETWEEN min AND max).    
162 LOG10 4 LOG10(X) Returns the base-10 logarithm of X. mysql> SELECT LOG10(2); -> 0.301030 mysql> SELECT LOG10(100); -> 2.000000 mysql> SELECT LOG10(-100); -> NULL  
163 SQRT 4 SQRT(X) Returns the non-negative square root of X. mysql> SELECT SQRT(4); -> 2.000000 mysql> SELECT SQRT(20); -> 4.472136  
164 DECIMAL 1 DECIMAL[(M[,D])] [UNSIGNED] [ZEROFILL] For MySQL 5.0.3 and above: A packed ``exact'' fixed-point number. M is the total number of digits and D is the number of decimals. The decimal point and (for negative numbers) the '-' sign are not counted in M. If D is 0, values have no decimal point or fractional part. The maximum number of digits (M) for DECIMAL is 64. The maximum number of supported decimals (D) is 30. If UNSIGNED is specified, negative values are disallowed. If D is omitted, the default is 0. If M is omitted, the default is 10. All basic calculations (+, -, *, /) with DECIMAL columns are done with a precision of 64 decimal digits. Before MySQL 5.0.3: An unpacked fixed-point number. Behaves like a CHAR column; ``unpacked'' means the number is stored as a string, using one character for each digit of the value. M is the total number of digits and D is the number of decimals. The decimal point and (for negative numbers) the '-' sign are not counted in M, although space for them is reserved. If D is 0, values have no decimal point or fractional part. The maximum range of DECIMAL values is the same as for DOUBLE, but the actual range for a given DECIMAL column may be constrained by the choice of M and D. If UNSIGNED is specified, negative values are disallowed. If D is omitted, the default is 0. If M is omitted, the default is 10. Before MySQL 3.23: As just described, with the exception that the M value must be large enough to include the space needed for the sign and the decimal point characters. DEC[(M[,D])] [UNSIGNED] [ZEROFILL] NUMERIC[(M[,D])] [UNSIGNED] [ZEROFILL] FIXED[(M[,D])] [UNSIGNED] [ZEROFILL] These are synonyms for DECIMAL. The FIXED synonym was added in MySQL 4.1.0 for compatibility with other servers.    
165 GEOMETRYN 5 GeometryN(gc,n) Returns the n-th geometry in the GeometryCollection value gc. Geometry numbers begin at 1. mysql> SET @gc = 'GeometryCollection(Point(1 1),LineString(2 2, 3 3))'; mysql> SELECT AsText(GeometryN(GeomFromText(@gc),1)); +----------------------------------------+ | AsText(GeometryN(GeomFromText(@gc),1)) | +----------------------------------------+ | POINT(1 1) | +----------------------------------------+  
166 CREATE INDEX 28 In MySQL 3.22 or later, CREATE INDEX is mapped to an ALTER TABLE statement to create indexes. See also : [ALTER TABLE, , ALTER TABLE]. The CREATE INDEX statement doesn't do anything prior to MySQL 3.22. CREATE [UNIQUE|FULLTEXT|SPATIAL] INDEX index_name [USING index_type] ON tbl_name (index_col_name,...) index_col_name: col_name [(length)] [ASC | DESC]  
167 ALTER DATABASE 28 ALTER DATABASE allows you to change the overall characteristics of a database. These characteristics are stored in the *db.opt file in the database directory. To use ALTER DATABASE, you need the ALTER privilege on the database. ALTER {DATABASE | SCHEMA} [db_name] alter_specification [, alter_specification] ... alter_specification: [DEFAULT] CHARACTER SET charset_name | [DEFAULT] COLLATE collation_name  
168 << 27 Shifts a longlong (BIGINT) number to the left. << mysql> SELECT 1 << 2; -> 4  
169 MD5 17 MD5(str) Calculates an MD5 128-bit checksum for the string. The value is returned as a binary string of 32 hex digits, or NULL if the argument was NULL. The return value can, for example, be used as a hash key. mysql> SELECT MD5('testing'); -> 'ae2b1fca515949e5d54fb22b8ed95575'  
170 < 26 < Less than: mysql> SELECT 2 < 2; -> 0  
171 UNIX_TIMESTAMP 14 UNIX_TIMESTAMP() UNIX_TIMESTAMP(date) If called with no argument, returns a Unix timestamp (seconds since '1970-01-01 00:00:00' GMT) as an unsigned integer. If UNIX_TIMESTAMP() is called with a date argument, it returns the value of the argument as seconds since '1970-01-01 00:00:00' GMT. date may be a DATE string, a DATETIME string, a TIMESTAMP, or a number in the format YYMMDD or YYYYMMDD in local time. mysql> SELECT UNIX_TIMESTAMP(); -> 882226357 mysql> SELECT UNIX_TIMESTAMP('1997-10-04 22:23:00'); -> 875996580  
172 DAYOFMONTH 14 DAYOFMONTH(date) Returns the day of the month for date, in the range 1 to 31. mysql> SELECT DAYOFMONTH('1998-02-03'); -> 3  
173 ASCII 23 ASCII(str) Returns the numeric value of the leftmost character of the string str. Returns 0 if str is the empty string. Returns NULL if str is NULL. ASCII() works for characters with numeric values from 0 to 255. mysql> SELECT ASCII('2'); -> 50 mysql> SELECT ASCII(2); -> 50 mysql> SELECT ASCII('dx'); -> 100  
174 DIV 4 Integer division. Similar to FLOOR() but safe with BIGINT values. mysql> SELECT 5 DIV 2; -> 2  
175 RENAME USER 7 The RENAME USER statement renames existing MySQL accounts. To use it, you must have the global CREATE USER privilege or the UPDATE privilege for the mysql database. An error occurs if any old account does not exist or any new account exists. The old_user and new_user values are given the same way as for the GRANT statement. RENAME USER old_user TO new_user [, old_user TO new_user] ...  
176 SHOW SLAVE STATUS 7 SHOW SLAVE STATUS Provides status information on essential parameters of the slave threads. If you issue this statement using the mysql client, you can use a \G statement terminator rather than semicolon to get a more readable vertical layout: mysql> SHOW SLAVE STATUS\G *************************** 1. row *************************** Slave_IO_State: Waiting for master to send event Master_Host: localhost Master_User: root Master_Port: 3306 Connect_Retry: 3 Master_Log_File: gbichot-bin.005 Read_Master_Log_Pos: 79 Relay_Log_File: gbichot-relay-bin.005 Relay_Log_Pos: 548 Relay_Master_Log_File: gbichot-bin.005 Slave_IO_Running: Yes Slave_SQL_Running: Yes Replicate_Do_DB: Replicate_Ignore_DB: Last_Errno: 0 Last_Error: Skip_Counter: 0 Exec_Master_Log_Pos: 79 Relay_Log_Space: 552 Until_Condition: None Until_Log_File: Until_Log_Pos: 0 Master_SSL_Allowed: No Master_SSL_CA_File: Master_SSL_CA_Path: Master_SSL_Cert: Master_SSL_Cipher: Master_SSL_Key: Seconds_Behind_Master: 8    
177 GEOMETRY 24 MySQL provides a standard way of creating spatial columns for geometry types, for example, with CREATE TABLE or ALTER TABLE. Currently, spatial columns are supported only for MyISAM tables. mysql> CREATE TABLE geom (g GEOMETRY); Query OK, 0 rows affected (0.02 sec)  
178 NUMPOINTS 18 NumPoints(ls) Returns the number of points in the LineString value ls. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT NumPoints(GeomFromText(@ls)); +------------------------------+ | NumPoints(GeomFromText(@ls)) | +------------------------------+ | 3 | +------------------------------+  
179 & 27 & Bitwise AND: mysql> SELECT 29 & 15; -> 13  
180 LOCALTIMESTAMP 14 LOCALTIMESTAMP LOCALTIMESTAMP() LOCALTIMESTAMP and LOCALTIMESTAMP() are synonyms for NOW().    
181 ADDDATE 14 ADDDATE(date,INTERVAL expr type) ADDDATE(expr,days) When invoked with the INTERVAL form of the second argument, ADDDATE() is a synonym for DATE_ADD(). The related function SUBDATE() is a synonym for DATE_SUB(). For information on the INTERVAL argument, see the discussion for DATE_ADD(). mysql> SELECT DATE_ADD('1998-01-02', INTERVAL 31 DAY); -> '1998-02-02' mysql> SELECT ADDDATE('1998-01-02', INTERVAL 31 DAY); -> '1998-02-02' As of MySQL 4.1.1, the second syntax is allowed, where expr is a date or datetime expression and days is the number of days to be added to expr. mysql> SELECT ADDDATE('1998-01-02', 31); -> '1998-02-02'    
182 SMALLINT 1 SMALLINT[(M)] [UNSIGNED] [ZEROFILL] A small integer. The signed range is -32768 to 32767. The unsigned range is 0 to 65535.    
183 ORD 23 ORD(str) If the leftmost character of the string str is a multi-byte character, returns the code for that character, calculated from the numeric values of its constituent bytes using this formula: (1st byte code) + (2nd byte code * 256) + (3rd byte code * 256^2) ... If the leftmost character is not a multi-byte character, ORD() returns the same value as the ASCII() function. mysql> SELECT ORD('2'); -> 50  
184 ENVELOPE 19 Envelope(g) Returns the Minimum Bounding Rectangle (MBR) for the geometry value g. The result is returned as a Polygon value. mysql> SELECT AsText(Envelope(GeomFromText('LineString(1 1,2 2)'))); +-------------------------------------------------------+ | AsText(Envelope(GeomFromText('LineString(1 1,2 2)'))) | +-------------------------------------------------------+ | POLYGON((1 1,2 1,2 2,1 2,1 1)) | +-------------------------------------------------------+ The polygon is defined by the corner points of the bounding box: POLYGON((MINX MINY, MAXX MINY, MAXX MAXY, MINX MAXY, MINX MINY))    
185 IS_FREE_LOCK 21 IS_FREE_LOCK(str) Checks whether the lock named str is free to use (that is, not locked). Returns 1 if the lock is free (no one is using the lock), 0 if the lock is in use, and NULL on errors (such as incorrect arguments).    
186 SHOW BINLOG 6 SHOW BINLOG EVENTS [IN 'log_name'] [FROM pos] [LIMIT [offset,] row_count] Shows the events in the binary log. If you do not specify 'log_name', the first binary log is displayed.    
187 TOUCHES 11 Touches(g1,g2) Returns 1 or 0 to indicate whether or not g1 spatially touches g2. Two geometries /spatially touch/ if the interiors of the geometries do not intersect, but the boundary of one of the geometries intersects either the boundary or the interior of the other.    
188 TIMESTAMPADD FUNCTION 14   mysql> SELECT TIMESTAMPADD(MINUTE,1,'2003-01-02'); -> '2003-01-02 00:01:00' mysql> SELECT TIMESTAMPADD(WEEK,1,'2003-01-02'); -> '2003-01-09'  
189 INET_ATON 21 INET_ATON(expr) Given the dotted-quad representation of a network address as a string, returns an integer that represents the numeric value of the address. Addresses may be 4- or 8-byte addresses. mysql> SELECT INET_ATON('209.207.224.40'); -> 3520061480  
190 AUTO_INCREMENT 1 The AUTO_INCREMENT attribute can be used to generate a unique identity for new rows: CREATE TABLE animals ( id MEDIUMINT NOT NULL AUTO_INCREMENT, name CHAR(30) NOT NULL, PRIMARY KEY (id) ); INSERT INTO animals (name) VALUES ('dog'),('cat'),('penguin'), ('lax'),('whale'),('ostrich'); SELECT * FROM animals;  
191 UNCOMPRESS 23 UNCOMPRESS(string_to_uncompress) Uncompresses a string compressed by the COMPRESS() function. If the argument is not a compressed value, the result is NULL. This function requires MySQL to have been compiled with a compression library such as zlib. Otherwise, the return value is always NULL. mysql> SELECT UNCOMPRESS(COMPRESS('any string')); -> 'any string' mysql> SELECT UNCOMPRESS('any string'); -> NULL  
192 ISSIMPLE 19 IsSimple(g) Currently, this function is a placeholder and should not be used. If implemented, its behavior will be as described in the next paragraph. Returns 1 if the geometry value g has no anomalous geometric points, such as self-intersection or self-tangency. IsSimple() returns 0 if the argument is not simple, and -1 if it is NULL. The description of each instantiable geometric class given earlier in the chapter includes the specific conditions that cause an instance of that class to be classified as not simple.    
193 - BINARY 4 - Subtraction: mysql> SELECT 3-5; -> -2  
194 GEOMCOLLFROMTEXT 3 GeomCollFromText(wkt[,srid]) GeometryCollectionFromText(wkt[,srid]) Constructs a GEOMETRYCOLLECTION value using its WKT representation and SRID.    
195 WKT DEFINITION 3 The Well-Known Text (WKT) representation of Geometry is designed to exchange geometry data in ASCII form.    
196 CURRENT_TIME 14 CURRENT_TIME CURRENT_TIME() CURRENT_TIME and CURRENT_TIME() are synonyms for CURTIME().    
197 LAST_INSERT_ID 25 LAST_INSERT_ID() LAST_INSERT_ID(expr) Returns the last automatically generated value that was inserted into an AUTO_INCREMENT column. mysql> SELECT LAST_INSERT_ID(); -> 195  
198 LAST_DAY 14 LAST_DAY(date) Takes a date or datetime value and returns the corresponding value for the last day of the month. Returns NULL if the argument is invalid. mysql> SELECT LAST_DAY('2003-02-05'); -> '2003-02-28' mysql> SELECT LAST_DAY('2004-02-05'); -> '2004-02-29' mysql> SELECT LAST_DAY('2004-01-01 01:01:01'); -> '2004-01-31' mysql> SELECT LAST_DAY('2003-03-32'); -> NULL  
199 MEDIUMINT 1 MEDIUMINT[(M)] [UNSIGNED] [ZEROFILL] A medium-size integer. The signed range is -8388608 to 8388607. The unsigned range is 0 to 16777215.    
200 FLOOR 4 FLOOR(X) Returns the largest integer value not greater than X. mysql> SELECT FLOOR(1.23); -> 1 mysql> SELECT FLOOR(-1.23); -> -2  
201 RTRIM 23 RTRIM(str) Returns the string str with trailing space characters removed. mysql> SELECT RTRIM('barbar '); -> 'barbar'  
202 DEGREES 4 DEGREES(X) Returns the argument X, converted from radians to degrees. mysql> SELECT DEGREES(PI()); -> 180.000000  
203 EXPLAIN 6 The EXPLAIN statement can be used either as a synonym for DESCRIBE or as a way to obtain information about how MySQL executes a SELECT statement: --- The EXPLAIN tbl_name syntax is synonymous with DESCRIBE tbl_name or SHOW COLUMNS FROM tbl_name. --- When you precede a SELECT statement with the keyword EXPLAIN, MySQL explains how it would process the SELECT, providing information about how tables are joined and in which order. EXPLAIN tbl_name  
204 VARCHAR 1 [NATIONAL] VARCHAR(M) [BINARY] A variable-length string. M represents the maximum column length. The range of M is 1 to 255 before MySQL 4.0.2, 0 to 255 as of MySQL 4.0.2, and 0 to 65,535 as of MySQL 5.0.3. (The maximum actual length of a VARCHAR in MySQL 5.0 is determined by the maximum row size and the character set you use. The maximum effective length is 65,532 bytes.) Note: Before 5.0.3, trailing spaces were removed when VARCHAR values were stored, which differs from the standard SQL specification. From MySQL 4.1.0 to 5.0.2, a VARCHAR column with a length specification greater than 255 is converted to the smallest TEXT type that can hold values of the given length. For example, VARCHAR(500) is converted to TEXT, and VARCHAR(200000) is converted to MEDIUMTEXT. This is a compatibility feature. However, this conversion affects trailing-space removal. VARCHAR is shorthand for CHARACTER VARYING. As of MySQL 4.1.2, the BINARY attribute is shorthand for specifying the binary collation of the column character set. Sorting and comparison is based on numeric character values. Before 4.1.2, BINARY attribute causes the column to be treated as a binary string. Sorting and comparison is based on numeric byte values. Starting from MySQL 5.0.3, VARCHAR is stored with a one-byte or two-byte length prefix + data. The length prefix is two bytes if the VARCHAR column is declared with a length greater than 255.    
205 UNHEX 23 UNHEX(str) Does the opposite of HEX(str). That is, it interprets each pair of hexadecimal digits in the argument as a number and converts it to the character represented by the number. The resulting characters are returned as a binary string. mysql> SELECT UNHEX('4D7953514C'); -> 'MySQL' mysql> SELECT 0x4D7953514C; -> 'MySQL' mysql> SELECT UNHEX(HEX('string')); -> 'string' mysql> SELECT HEX(UNHEX('1267')); -> '1267'  
206 - UNARY 4 - Unary minus. Changes the sign of the argument. mysql> SELECT - 2; -> -2  
207 COS 4 COS(X) Returns the cosine of X, where X is given in radians. mysql> SELECT COS(PI()); -> -1.000000  
208 DATE FUNCTION 14 DATE(expr) Extracts the date part of the date or datetime expression expr. mysql> SELECT DATE('2003-12-31 01:02:03'); -> '2003-12-31'  
209 RESET MASTER 6 RESET MASTER Deletes all binary logs listed in the index file, resets the binary log index file to be empty, and creates a new binary log file. This statement was named FLUSH MASTER before MySQL 3.23.26.    
210 TAN 4 TAN(X) Returns the tangent of X, where X is given in radians. mysql> SELECT TAN(PI()+1); -> 1.557408  
211 PI 4 PI() Returns the value of PI. The default number of decimals displayed is five, but MySQL internally uses the full double-precision value for PI. mysql> SELECT PI(); -> 3.141593 mysql> SELECT PI()+0.000000000000000000; -> 3.141592653589793116  
212 WEEKOFYEAR 14 WEEKOFYEAR(date) Returns the calendar week of the date as a number in the range from 1 to 53. It is a compatibility function that is equivalent to WEEK(date,3). mysql> SELECT WEEKOFYEAR('1998-02-20'); -> 8  
213 / 4 / Division: mysql> SELECT 3/5; -> 0.60  
214 STDDEV_SAMP 12 STDDEV_SAMP(expr) Returns the sample standard deviation of expr (the square root of VAR_SAMP(). This function was added in MySQL 5.0.3.    
215 MLINEFROMWKB 13 MLineFromWKB(wkb[,srid]) MultiLineStringFromWKB(wkb[,srid]) Constructs a MULTILINESTRING value using its WKB representation and SRID.    
216 UNCOMPRESSED_LENGTH 23 UNCOMPRESSED_LENGTH(compressed_string) Returns the length of a compressed string before compression. mysql> SELECT UNCOMPRESSED_LENGTH(COMPRESS(REPEAT('a',30))); -> 30  
217 LOG2 4 LOG2(X) Returns the base-2 logarithm of X. mysql> SELECT LOG2(65536); -> 16.000000 mysql> SELECT LOG2(-100); -> NULL  
218 SUBTIME 14 SUBTIME(expr,expr2) SUBTIME() subtracts expr2 from expr and returns the result. expr is a time or datetime expression, and expr2 is a time expression. mysql> SELECT SUBTIME('1997-12-31 23:59:59.999999', -> '1 1:1:1.000002'); -> '1997-12-30 22:58:58.999997' mysql> SELECT SUBTIME('01:00:00.999999', '02:00:00.999998'); -> '-00:59:59.999999'  
219 DROP TABLE 28 DROP TABLE removes one or more tables. You must have the DROP privilege for each table. All table data and the table definition are /removed/, so /be careful/ with this statement! In MySQL 3.22 or later, you can use the keywords IF EXISTS to prevent an error from occurring for tables that don't exist. As of MySQL 4.1, a NOTE is generated for each non-existent table when using IF EXISTS. See also : [SHOW WARNINGS, , SHOW WARNINGS]. RESTRICT and CASCADE are allowed to make porting easier. For the moment, they do nothing. Note: DROP TABLE automatically commits the current active transaction, unless you are using MySQL 4.1 or higher and the TEMPORARY keyword. DROP [TEMPORARY] TABLE [IF EXISTS] tbl_name [, tbl_name] ... [RESTRICT | CASCADE]  
220 DUAL 22 SELECT ... FROM DUAL is an alias for SELECT .... (To be compatible with some other databases).    
221 INSTR 23 INSTR(str,substr) Returns the position of the first occurrence of substring substr in string str. This is the same as the two-argument form of LOCATE(), except that the arguments are swapped. mysql> SELECT INSTR('foobarbar', 'bar'); -> 4 mysql> SELECT INSTR('xbar', 'foobar'); -> 0  
222 NOW 14 NOW() Returns the current date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT NOW(); -> '1997-12-15 23:50:26' mysql> SELECT NOW() + 0; -> 19971215235026  
223 >= 26 >= Greater than or equal: mysql> SELECT 2 >= 2; -> 1  
224 EXP 4 EXP(X) Returns the value of e (the base of natural logarithms) raised to the power of X. mysql> SELECT EXP(2); -> 7.389056 mysql> SELECT EXP(-2); -> 0.135335  
225 SHA 17 SHA1(str) SHA(str) Calculates an SHA1 160-bit checksum for the string, as described in RFC 3174 (Secure Hash Algorithm). The value is returned as a string of 40 hex digits, or NULL if the argument was NULL. One of the possible uses for this function is as a hash key. You can also use it as a cryptographically safe function for storing passwords. mysql> SELECT SHA1('abc'); -> 'a9993e364706816aba3e25717850c26c9cd0d89d'  
226 LONGBLOB 1 LONGBLOB A BLOB column with a maximum length of 4,294,967,295 or 4GB (2^32 - 1) bytes. Up to MySQL 3.23, the client/server protocol and MyISAM tables had a limit of 16MB per communication packet / table row. From MySQL 4.0, the maximum allowed length of LONGBLOB columns depends on the configured maximum packet size in the client/server protocol and available memory.    
227 POINTN 18 PointN(ls,n) Returns the n-th point in the Linestring value ls. Point numbers begin at 1. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT AsText(PointN(GeomFromText(@ls),2)); +-------------------------------------+ | AsText(PointN(GeomFromText(@ls),2)) | +-------------------------------------+ | POINT(2 2) | +-------------------------------------+  
228 SUM 12 SUM([DISTINCT] expr) Returns the sum of expr. If the return set has no rows, SUM() returns NULL. The DISTINCT keyword can be used as of MySQL 5.0.0 to sum only the distinct values of expr.    
229 OCT 23 OCT(N) Returns a string representation of the octal value of N, where N is a longlong (BIGINT)number. This is equivalent to CONV(N,10,8). Returns NULL if N is NULL. mysql> SELECT OCT(12); -> '14'  
230 SYSDATE 14 SYSDATE() SYSDATE() is a synonym for NOW().    
231 ASBINARY 13 AsBinary(g) Converts a value in internal geometry format to its WKB representation and returns the binary result. SELECT AsBinary(g) FROM geom;  
232 MAKEDATE 14 MAKEDATE(year,dayofyear) Returns a date, given year and day-of-year values. dayofyear must be greater than 0 or the result is NULL. mysql> SELECT MAKEDATE(2001,31), MAKEDATE(2001,32); -> '2001-01-31', '2001-02-01' mysql> SELECT MAKEDATE(2001,365), MAKEDATE(2004,365); -> '2001-12-31', '2004-12-30' mysql> SELECT MAKEDATE(2001,0); -> NULL  
233 BINARY OPERATOR 23 BINARY The BINARY operator casts the string following it to a binary string. This is an easy way to force a column comparison to be done byte by byte rather than character by character. This causes the comparison to be case sensitive even if the column isn't defined as BINARY or BLOB. BINARY also causes trailing spaces to be significant. mysql> SELECT 'a' = 'A'; -> 1 mysql> SELECT BINARY 'a' = 'A'; -> 0 mysql> SELECT 'a' = 'a '; -> 1 mysql> SELECT BINARY 'a' = 'a '; -> 0  
234 MBROVERLAPS 8 MBROverlaps(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangles of the two geometries g1 and g2 overlap.    
235 SOUNDEX 23 SOUNDEX(str) Returns a soundex string from str. Two strings that sound almost the same should have identical soundex strings. A standard soundex string is four characters long, but the SOUNDEX() function returns an arbitrarily long string. You can use SUBSTRING() on the result to get a standard soundex string. All non-alphabetic characters are ignored in the given string. All international alphabetic characters outside the A-Z range are treated as vowels. mysql> SELECT SOUNDEX('Hello'); -> 'H400' mysql> SELECT SOUNDEX('Quadratically'); -> 'Q36324'  
236 SHOW MASTER LOGS 6 SHOW MASTER LOGS SHOW BINARY LOGS Lists the binary log files on the server. This statement is used as part of the procedure described in [PURGE MASTER LOGS, , PURGE MASTER LOGS] for determining which logs can be purged. mysql> SHOW BINARY LOGS; +---------------+-----------+ | Log_name | File_size | +---------------+-----------+ | binlog.000015 | 724935 | | binlog.000016 | 733481 | +---------------+-----------+    
237 MBRTOUCHES 8 MBRTouches(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangles of the two geometries g1 and g2 touch.    
238 INSERT SELECT 6 INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE] [INTO] tbl_name [(col_name,...)] SELECT ... [ ON DUPLICATE KEY UPDATE col_name=expr, ... ] With INSERT ... SELECT, you can quickly insert many rows into a table from one or many tables. INSERT INTO tbl_temp2 (fld_id) SELECT tbl_temp1.fld_order_id FROM tbl_temp1 WHERE tbl_temp1.fld_order_id > 100;  
239 VARBINARY 1 VARBINARY(M) The VARBINARY type is similar to the VARCHAR type, but stores binary byte strings rather than non-binary character strings. This type was added in MySQL 4.1.2.    
240 LOAD INDEX 6 The LOAD INDEX INTO CACHE statement preloads a table index into the key cache to which it has been assigned by an explicit CACHE INDEX statement, or into the default key cache otherwise. LOAD INDEX INTO CACHE is used only for MyISAM tables. The IGNORE LEAVES modifier causes only blocks for the non-leaf nodes of the index to be preloaded. LOAD INDEX INTO CACHE tbl_index_list [, tbl_index_list] ... tbl_index_list: tbl_name [[INDEX|KEY] (index_name[, index_name] ...)] [IGNORE LEAVES]  
241 UNION 6 UNION is used to combine the result from many SELECT statements into one result set. UNION is available from MySQL 4.0.0 on. Selected columns listed in corresponding positions of each SELECT statement should have the same type. (For example, the first column selected by the first statement should have the same type as the first column selected by the other statements.) The column names used in the first SELECT statement are used as the column names for the results returned. SELECT ... UNION [ALL | DISTINCT] SELECT ... [UNION [ALL | DISTINCT] SELECT ...]  
242 TO_DAYS 14 TO_DAYS(date) Given a date date, returns a daynumber (the number of days since year 0). mysql> SELECT TO_DAYS(950501); -> 728779 mysql> SELECT TO_DAYS('1997-10-07'); -> 729669  
243 NOT REGEXP 23 expr NOT REGEXP pat expr NOT RLIKE pat This is the same as NOT (expr REGEXP pat).    
244 NOT IN 26 expr NOT IN (value,...) This is the same as NOT (expr IN (value,...)).    
245 ! 20 NOT ! Logical NOT. Evaluates to 1 if the operand is 0, to 0 if the operand is non-zero, and NOT NULL returns NULL. mysql> SELECT NOT 10; -> 0 mysql> SELECT NOT 0; -> 1 mysql> SELECT NOT NULL; -> NULL mysql> SELECT ! (1+1); -> 0 mysql> SELECT ! 1+1; -> 1  
246 TEXT TYPE 1 TEXT[(M)] A TEXT column with a maximum length of 65,535 (2^16 - 1) characters. Beginning with MySQL 4.1, an optional length M can be given. MySQL will create the column as the smallest TEXT type largest enough to hold values M characters long.    
247 DOUBLE 1 DOUBLE[(M,B)] [UNSIGNED] [ZEROFILL] A normal-size (double-precision) floating-point number. Allowable values are -1.7976931348623157E+308 to -2.2250738585072014E-308, 0, and 2.2250738585072014E-308 to 1.7976931348623157E+308. If UNSIGNED is specified, negative values are disallowed. M is the display width and B is the number of bits of precision. DOUBLE without arguments or FLOAT(p) (where p is in the range from 25 to 53) stands for a double-precision floating-point number. A single-precision floating-point number is accurate to approximately 7 decimal places; a double-precision floating-point number is accurate to approximately 15 decimal places. DOUBLE PRECISION[(M,D)] [UNSIGNED] [ZEROFILL] REAL[(M,D)] [UNSIGNED] [ZEROFILL] These are synonyms for DOUBLE. Exception: If the server SQL mode includes the REAL_AS_FLOAT option, REAL is a synonym for FLOAT rather than DOUBLE.    
248 TIME 1 TIME A time. The range is '-838:59:59' to '838:59:59'. MySQL displays TIME values in 'HH:MM:SS' format, but allows you to assign values to TIME columns using either strings or numbers.    
249 && 20 AND && Logical AND. Evaluates to 1 if all operands are non-zero and not NULL, to 0 if one or more operands are 0, otherwise NULL is returned. mysql> SELECT 1 && 1; -> 1 mysql> SELECT 1 && 0; -> 0 mysql> SELECT 1 && NULL; -> NULL mysql> SELECT 0 && NULL; -> 0 mysql> SELECT NULL && 0; -> 0  
250 X 16 X(p) Returns the X-coordinate value for the point p as a double-precision number. mysql> SELECT X(GeomFromText('Point(56.7 53.34)')); +--------------------------------------+ | X(GeomFromText('Point(56.7 53.34)')) | +--------------------------------------+ | 56.7 | +--------------------------------------+  
251 FOUND_ROWS 25 A SELECT statement may include a LIMIT clause to restrict the number of rows the server returns to the client. In some cases, it is desirable to know how many rows the statement would have returned without the LIMIT, but without running the statement again. To get this row count, include a SQL_CALC_FOUND_ROWS option in the SELECT statement, then invoke FOUND_ROWS() afterward: mysql> SELECT SQL_CALC_FOUND_ROWS * FROM tbl_name -> WHERE id > 100 LIMIT 10; mysql> SELECT FOUND_ROWS();  
252 SYSTEM_USER 25 SYSTEM_USER() SYSTEM_USER() is a synonym for USER().    
253 CROSSES 11 Crosses(g1,g2) Returns 1 if g1 spatially crosses g2. Returns NULL if g1 is a Polygon or a MultiPolygon, or if g2 is a Point or a MultiPoint. Otherwise, returns 0. The term /spatially crosses/ denotes a spatial relation between two given geometries that has the following properties: --- The two geometries intersect --- Their intersection results in a geometry that has a dimension that is one less than the maximum dimension of the two given geometries --- Their intersection is not equal to either of the two given geometries    
254 TRUNCATE TABLE 6 TRUNCATE TABLE empties a table completely. Logically, this is equivalent to a DELETE statement that deletes all rows, but there are practical differences under some circumstances. For InnoDB before version 5.0.3, TRUNCATE TABLE is mapped to DELETE, so there is no difference. Starting with MySQL/InnoDB-5.0.3, fast TRUNCATE TABLE is available. The operation is still mapped to DELETE if there are foreign key constraints that reference the table. For other storage engines, TRUNCATE TABLE differs from DELETE FROM in the following ways from MySQL 4.0 and up: --- Truncate operations drop and re-create the table, which is much faster than deleting rows one by one. --- Truncate operations are not transaction-safe; you get an error if you have an active transaction or an active table lock. --- The number of deleted rows is not returned. --- As long as the table definition file *tbl_name.frm is valid, the table can be re-created as an empty table with TRUNCATE TABLE, even if the data or index files have become corrupted. --- The table handler does not remember the last used AUTO_INCREMENT value, but starts counting from the beginning. This is true even for MyISAM and InnoDB, which normally does not reuse sequence values. In MySQL 3.23, TRUNCATE TABLE is mapped to COMMIT; DELETE FROM tbl_name, so it behaves like DELETE. See also : [DELETE, , DELETE]. TRUNCATE TABLE is an Oracle SQL extension. This statement was added in MySQL 3.23.28, although from 3.23.28 to 3.23.32, the keyword TABLE must be omitted. TRUNCATE TABLE tbl_name  
255 CURRENT_DATE 14 CURRENT_DATE CURRENT_DATE() CURRENT_DATE and CURRENT_DATE() are synonyms for CURDATE().    
256 BIT_XOR 12 BIT_XOR(expr) Returns the bitwise XOR of all bits in expr. The calculation is performed with 64-bit (BIGINT) precision.    
257 AREA 0 Area(poly) Returns as a double-precision number the area of the Polygon value poly, as measured in its spatial reference system. mysql> SET @poly = 'Polygon((0 0,0 3,3 0,0 0),(1 1,1 2,2 1,1 1))'; mysql> SELECT Area(GeomFromText(@poly)); +---------------------------+ | Area(GeomFromText(@poly)) | +---------------------------+ | 4 | +---------------------------+  
258 START SLAVE 7 START SLAVE [thread_type [, thread_type] ... ] START SLAVE [SQL_THREAD] UNTIL MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS = log_pos START SLAVE [SQL_THREAD] UNTIL RELAY_LOG_FILE = 'log_name', RELAY_LOG_POS = log_pos thread_type: IO_THREAD | SQL_THREAD START SLAVE with no options starts both of the slave threads. The I/O thread reads queries from the master server and stores them in the relay log. The SQL thread reads the relay log and executes the queries. START SLAVE requires the SUPER privilege. If START SLAVE succeeds in starting the slave threads, it returns without any error. However, even in that case, it might be that the slave threads start and then later stop (for example, because they don't manage to connect to the master or read its binary logs, or some other problem). START SLAVE does not warn you about this. You must check your slave's error log for error messages generated by the slave threads, or check that they are running fine with SHOW SLAVE STATUS.    
259 FLUSH 6 You should use the FLUSH statement if you want to clear some of the internal caches MySQL uses. To execute FLUSH, you must have the RELOAD privilege. FLUSH [LOCAL | NO_WRITE_TO_BINLOG] flush_option [, flush_option] ...  
260 DESCRIBE 7 {DESCRIBE | DESC} tbl_name [col_name | wild] DESCRIBE provides information about the columns in a table. It is a shortcut for SHOW COLUMNS FROM. As of MySQL 5.0.1, these statements also display information for views.    
261 STDDEV_POP 12 STDDEV_POP(expr) Returns the population standard deviation of expr (the square root of VAR_POP()). This function was added in MySQL 5.0.3. Before 5.0.3, you can use STD() or STDDEV(), which are equivalent but not standard SQL.    
262 SUBSTRING 23 SUBSTRING(str,pos) SUBSTRING(str FROM pos) SUBSTRING(str,pos,len) SUBSTRING(str FROM pos FOR len) The forms without a len argument return a substring from string str starting at position pos. The forms with a len argument return a substring len characters long from string str, starting at position pos. The forms that use FROM are standard SQL syntax. mysql> SELECT SUBSTRING('Quadratically',5); -> 'ratically' mysql> SELECT SUBSTRING('foobarbar' FROM 4); -> 'barbar' mysql> SELECT SUBSTRING('Quadratically',5,6); -> 'ratica'  
263 ISEMPTY 19 IsEmpty(g) Returns 1 if the geometry value g is the empty geometry, 0 if it is not empty, and -1 if the argument is NULL. If the geometry is empty, it represents the empty point set.    
264 LTRIM 23 LTRIM(str) Returns the string str with leading space characters removed. mysql> SELECT LTRIM(' barbar'); -> 'barbar'  
265 REPAIR 7 REPAIR TABLE repairs a possibly corrupted table. By default, it has the same effect as myisamchk --recover tbl_name. REPAIR TABLE works only on MyISAM tables. REPAIR [LOCAL | NO_WRITE_TO_BINLOG] TABLE tbl_name [, tbl_name] ... [QUICK] [EXTENDED] [USE_FRM]  
266 INTERSECTS 11 Intersects(g1,g2) Returns 1 or 0 to indicate whether or not g1 spatially intersects g2.    
267 MBRDISJOINT 8 MBRDisjoint(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangles of the two geometries g1 and g2 are disjoint (do not intersect).    
268 SUBSTRING_INDEX 23 SUBSTRING_INDEX(str,delim,count) Returns the substring from string str before count occurrences of the delimiter delim. If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned. mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2); -> 'www.mysql' mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2); -> 'mysql.com'  
269 ENCODE 17 ENCODE(str,pass_str) Encrypt str using pass_str as the password. To decrypt the result, use DECODE(). The result is a binary string of the same length as str. If you want to save it in a column, use a BLOB column type.    
270 TRUNCATE 4 TRUNCATE(X,D) Returns the number X, truncated to D decimals. If D is 0, the result has no decimal point or fractional part. D can be negative to truncate (make zero) D digits left of the decimal point of the value X. mysql> SELECT TRUNCATE(1.223,1); -> 1.2 mysql> SELECT TRUNCATE(1.999,1); -> 1.9 mysql> SELECT TRUNCATE(1.999,0); -> 1 mysql> SELECT TRUNCATE(-1.999,1); -> -1.9 mysql> SELECT TRUNCATE(122,-2); -> 100  
271 TIMESTAMPADD 14 TIMESTAMPADD(interval,int_expr,datetime_expr) Adds the integer expression int_expr to the date or datetime expression datetime_expr. The unit for int_expr is given by the interval argument, which should be one of the following values: FRAC_SECOND, SECOND, MINUTE, HOUR, DAY, WEEK, MONTH, QUARTER, or YEAR. The interval value may be specified using one of keywords as shown, or with a prefix of SQL_TSI_. For example, DAY or SQL_TSI_DAY both are legal.    
272 SHOW 6 SHOW has many forms that provide information about databases, tables, columns, or status information about the server. This section describes those following: SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [LIKE 'pattern'] SHOW CREATE DATABASE db_name SHOW CREATE TABLE tbl_name SHOW DATABASES [LIKE 'pattern'] SHOW ENGINE engine_name {LOGS | STATUS } SHOW [STORAGE] ENGINES SHOW ERRORS [LIMIT [offset,] row_count] SHOW GRANTS FOR user SHOW INDEX FROM tbl_name [FROM db_name] SHOW INNODB STATUS SHOW [BDB] LOGS SHOW PRIVILEGES SHOW [FULL] PROCESSLIST SHOW [GLOBAL | SESSION] STATUS [LIKE 'pattern'] SHOW TABLE STATUS [FROM db_name] [LIKE 'pattern'] SHOW [OPEN] TABLES [FROM db_name] [LIKE 'pattern'] SHOW [GLOBAL | SESSION] VARIABLES [LIKE 'pattern'] SHOW WARNINGS [LIMIT [offset,] row_count] The SHOW statement also has forms that provide information about replication master and slave servers and are described in [Replication SQL]: SHOW BINLOG EVENTS SHOW MASTER LOGS SHOW MASTER STATUS SHOW SLAVE HOSTS SHOW SLAVE STATUS If the syntax for a given SHOW statement includes a LIKE 'pattern' part, 'pattern' is a string that can contain the SQL '%' and '_' wildcard characters. The pattern is useful for restricting statement output to matching values.    
273 GREATEST 26 GREATEST(value1,value2,...) With two or more arguments, returns the largest (maximum-valued) argument. The arguments are compared using the same rules as for LEAST(). mysql> SELECT GREATEST(2,0); -> 2 mysql> SELECT GREATEST(34.0,3.0,5.0,767.0); -> 767.0 mysql> SELECT GREATEST('B','A','C'); -> 'C'  
274 OCTETLENGTH 23 OCTET_LENGTH(str) OCTET_LENGTH() is a synonym for LENGTH().    
275 SECOND 14 SECOND(time) Returns the second for time, in the range 0 to 59. mysql> SELECT SECOND('10:05:03'); -> 3  
276 BIT_AND 12 BIT_AND(expr) Returns the bitwise AND of all bits in expr. The calculation is performed with 64-bit (BIGINT) precision. mysql> SELECT order.custid, customer.name, MAX(payments) -> FROM order,customer -> WHERE order.custid = customer.custid -> GROUP BY order.custid;  
277 ATAN2 4 ATAN(Y,X) ATAN2(Y,X) Returns the arc tangent of the two variables X and Y. It is similar to calculating the arc tangent of Y / X, except that the signs of both arguments are used to determine the quadrant of the result. mysql> SELECT ATAN(-2,2); -> -0.785398 mysql> SELECT ATAN2(PI(),0); -> 1.570796  
278 MBRCONTAINS 8 MBRContains(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangle of g1 contains the Minimum Bounding Rectangle of g2. mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))'); mysql> SET @g2 = GeomFromText('Point(1 1)'); mysql> SELECT MBRContains(@g1,@g2), MBRContains(@g2,@g1); ----------------------+----------------------+ | MBRContains(@g1,@g2) | MBRContains(@g2,@g1) | +----------------------+----------------------+ | 1 | 0 | +----------------------+----------------------+  
279 HOUR 14 HOUR(time) Returns the hour for time. The range of the return value is 0 to 23 for time-of-day values. mysql> SELECT HOUR('10:05:03'); -> 10  
280 TYPE SET 1 SET('value1','value2',...) A set. A string object that can have zero or more values, each of which must be chosen from the list of values 'value1', 'value2', ... A SET column can have a maximum of 64 members. SET values are represented internally as integers.    
281 SELECT 6 SELECT is used to retrieve rows selected from one or more tables. Support for UNION statements and subqueries is available as of MySQL 4.0 and 4.1, respectively. See [UNION, , UNION] and [Subqueries]. --- Each select_expr indicates a column you want to retrieve. --- table_references indicates the table or tables from which to retrieve rows. Its syntax is described in [JOIN, , JOIN]. --- where_definition consists of the keyword WHERE followed by an expression that indicates the condition or conditions that rows must satisfy to be selected. SELECT can also be used to retrieve rows computed without reference to any table. SELECT [ALL | DISTINCT | DISTINCTROW ] [HIGH_PRIORITY] [STRAIGHT_JOIN] [SQL_SMALL_RESULT] [SQL_BIG_RESULT] [SQL_BUFFER_RESULT] [SQL_CACHE | SQL_NO_CACHE] [SQL_CALC_FOUND_ROWS] select_expr, ... [INTO OUTFILE 'file_name' export_options | INTO DUMPFILE 'file_name'] [FROM table_references [WHERE where_definition] [GROUP BY {col_name | expr | position} [ASC | DESC], ... [WITH ROLLUP]] [HAVING where_definition] [ORDER BY {col_name | expr | position} [ASC | DESC] , ...] [LIMIT {[offset,] row_count | row_count OFFSET offset}] [PROCEDURE procedure_name(argument_list)] [FOR UPDATE | LOCK IN SHARE MODE]]  
282 COT 4 COT(X) Returns the cotangent of X. mysql> SELECT COT(12); -> -1.57267341 mysql> SELECT COT(0); -> NULL  
283 BACKUP TABLE 7 Note: This statement is deprecated. We are working on a better replacement for it that will provide online backup capabilities. In the meantime, the mysqlhotcopy script can be used instead. BACKUP TABLE copies to the backup directory the minimum number of table files needed to restore the table, after flushing any buffered changes to disk. The statement works only for MyISAM tables. It copies the *.frm definition and *.MYD data files. The *.MYI index file can be rebuilt from those two files. The directory should be specified as a full pathname. BACKUP TABLE tbl_name [, tbl_name] ... TO '/path/to/backup/directory'  
284 LOAD_FILE 23 LOAD_FILE(file_name) Reads the file and returns the file contents as a string. The file must be located on the server, you must specify the full pathname to the file, and you must have the FILE privilege. The file must be readable by all and be smaller than max_allowed_packet bytes. If the file doesn't exist or cannot be read because one of the preceding conditions is not satisfied, the function returns NULL. mysql> UPDATE tbl_name SET blob_column=LOAD_FILE('/tmp/picture') WHERE id=1;  
285 POINTFROMTEXT 3 PointFromText(wkt[,srid]) Constructs a POINT value using its WKT representation and SRID.    
286 LOAD TABLE FROM MASTER 6 LOAD TABLE tbl_name FROM MASTER Transfers a copy of the table from master to the slave. This statement is implemented mainly for debugging of LOAD DATA FROM MASTER. It requires that the account used for connecting to the master server has the RELOAD and SUPER privileges on the master and the SELECT privilege on the master table to load. On the slave side, the user that issues LOAD TABLE FROM MASTER should have privileges to drop and create the table. The conditions for LOAD DATA FROM MASTER apply here, too. For example, LOAD TABLE FROM MASTER works only for MyISAM tables. The timeout notes for LOAD DATA FROM MASTER apply as well.    
287 GROUP_CONCAT 12 GROUP_CONCAT(expr) This function returns a string result with the concatenated non-NULL values from a group. It returns NULL if there are no non-NULL values. The full syntax is as follows: GROUP_CONCAT([DISTINCT] expr [,expr ...] [ORDER BY {unsigned_integer | col_name | expr} [ASC | DESC] [,col_name ...]] [SEPARATOR str_val]) mysql> SELECT student_name, -> GROUP_CONCAT(test_score) -> FROM student -> GROUP BY student_name;  
288 DATE_FORMAT 14 DATE_FORMAT(date,format) Formats the date value according to the format string. The following specifiers may be used in the format string: Specifier Description %a Abbreviated weekday name (Sun..Sat) %b Abbreviated month name (Jan..Dec) %c Month, numeric (0..12) %D Day of the month with English suffix (0th, 1st, 2nd, 3rd, ...) %d Day of the month, numeric (00..31) %e Day of the month, numeric (0..31) %f Microseconds (000000..999999) %H Hour (00..23) %h Hour (01..12) %I Hour (01..12) %i Minutes, numeric (00..59) %j Day of year (001..366) %k Hour (0..23) %l Hour (1..12) %M Month name (January..December) %m Month, numeric (00..12) %p AM or PM %r Time, 12-hour (hh:mm:ss followed by AM or PM) %S Seconds (00..59) %s Seconds (00..59) %T Time, 24-hour (hh:mm:ss) %U Week (00..53), where Sunday is the first day of the week %u Week (00..53), where Monday is the first day of the week %V Week (01..53), where Sunday is the first day of the week; used with %X %v Week (01..53), where Monday is the first day of the week; used with %x %W Weekday name (Sunday..Saturday) %w Day of the week (0=Sunday..6=Saturday) %X Year for the week where Sunday is the first day of the week, numeric, four digits; used with %V %x Year for the week, where Monday is the first day of the week, numeric, four digits; used with %v %Y Year, numeric, four digits %y Year, numeric, two digits %% A literal '%'. All other characters are copied to the result without interpretation. The %v, %V, %x, and %X format specifiers are available as of MySQL 3.23.8. %f is available as of MySQL 4.1.1. As of MySQL 3.23, the '%' character is required before format specifier characters. In earlier versions of MySQL, '%' was optional. The reason the ranges for the month and day specifiers begin with zero is that MySQL allows incomplete dates such as '2004-00-00' to be stored as of MySQL 3.23. mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%W %M %Y'); -> 'Saturday October 1997' mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%H:%i:%s'); -> '22:23:00' mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%D %y %a %d %m %b %j'); -> '4th 97 Sat 04 10 Oct 277' mysql> SELECT DATE_FORMAT('1997-10-04 22:23:00', '%H %k %I %r %T %S %w'); -> '22 22 10 10:23:00 PM 22:23:00 00 6' mysql> SELECT DATE_FORMAT('1999-01-01', '%X %V'); -> '1998 52'  
289 BENCHMARK 25 BENCHMARK(count,expr) The BENCHMARK() function executes the expression expr repeatedly count times. It may be used to time how fast MySQL processes the expression. The result value is always 0. The intended use is from within the mysql client, which reports query execution times: mysql> SELECT BENCHMARK(1000000,ENCODE('hello','goodbye')); +----------------------------------------------+ | BENCHMARK(1000000,ENCODE('hello','goodbye')) | +----------------------------------------------+ | 0 | +----------------------------------------------+ 1 row in set (4.74 sec)  
290 YEAR 14 YEAR(date) Returns the year for date, in the range 1000 to 9999. mysql> SELECT YEAR('98-02-03'); -> 1998  
291 SHOW ENGINE 6 SHOW ENGINE displays log or status information about storage engines. The following statements currently are supported: SHOW ENGINE BDB LOGS SHOW ENGINE INNODB STATUS SHOW ENGINE BDB LOGS displays status information about existing BDB log files. It returns the following fields: File The full path to the log file. Type The log file type (BDB for Berkeley DB log files). Status The status of the log file (FREE if the file can be removed, or IN USE if the file is needed by the transaction subsystem) SHOW ENGINE INNODB STATUS displays extensive information about the state of the InnoDB storage engine. Older (and now deprecated) synonyms for these statements are SHOW [BDB] LOGS and SHOW INNODB STATUS. SHOW ENGINE can be used as of MySQL 4.1.2. SHOW ENGINE engine_name {LOGS | STATUS }  
292 RELEASE_LOCK 21 RELEASE_LOCK(str) Releases the lock named by the string str that was obtained with GET_LOCK(). Returns 1 if the lock was released, 0 if the lock wasn't locked by this thread (in which case the lock is not released), and NULL if the named lock didn't exist. The lock does not exist if it was never obtained by a call to GET_LOCK() or if it has previously been released. The DO statement is convenient to use with RELEASE_LOCK(). See also : [DO, , DO].    
293 IS NULL 26 IS NULL IS NOT NULL Tests whether a value is or is not NULL. mysql> SELECT 1 IS NULL, 0 IS NULL, NULL IS NULL; -> 0, 0, 1 mysql> SELECT 1 IS NOT NULL, 0 IS NOT NULL, NULL IS NOT NULL; -> 1, 1, 0  
294 CONVERT_TZ 14 CONVERT_TZ(dt,from_tz,to_tz) CONVERT_TZ() converts a datetime value dt from time zone given by from_tz to the time zone given by to_tz and returns the resulting value. Time zones may be specified as described in [Time zone support]. This function returns NULL if the arguments are invalid. mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','GMT','MET'); -> '2004-01-01 13:00:00' mysql> SELECT CONVERT_TZ('2004-01-01 12:00:00','+00:00','-07:00'); -> '2004-01-01 05:00:00'  
295 TIME_TO_SEC 14 TIME_TO_SEC(time) Returns the time argument, converted to seconds. mysql> SELECT TIME_TO_SEC('22:23:00'); -> 80580 mysql> SELECT TIME_TO_SEC('00:39:38'); -> 2378  
296 WEEKDAY 14 WEEKDAY(date) Returns the weekday index for date (0 = Monday, 1 = Tuesday, ... 6 = Sunday). mysql> SELECT WEEKDAY('1998-02-03 22:23:00'); -> 1 mysql> SELECT WEEKDAY('1997-11-05'); -> 2  
297 EXPORT_SET 23 EXPORT_SET(bits,on,off[,separator[,number_of_bits]]) Returns a string in which for every bit set in the value bits, you get an on string and for every reset bit you get an off string. Bits in bits are examined from right to left (from low-order to high-order bits). Strings are added to the result from left to right, separated by the separator string (default ','). The number of bits examined is given by number_of_bits (default 64). mysql> SELECT EXPORT_SET(5,'Y','N',',',4); -> 'Y,N,Y,N' mysql> SELECT EXPORT_SET(6,'1','0',',',10); -> '0,1,1,0,0,0,0,0,0,0'  
298 TIME FUNCTION 14 TIME(expr) Extracts the time part of the time or datetime expression expr. mysql> SELECT TIME('2003-12-31 01:02:03'); -> '01:02:03' mysql> SELECT TIME('2003-12-31 01:02:03.000123'); -> '01:02:03.000123'  
299 CAST 23 The CAST() and CONVERT() functions can be used to take a value of one type and produce a value of another type. The type can be one of the following values: --- BINARY --- CHAR --- DATE --- DATETIME --- SIGNED [INTEGER] --- TIME --- UNSIGNED [INTEGER] BINARY produces a binary string. See the entry for the BINARY operator in this section for a description of how this affects comparisons. CAST() and CONVERT() are available as of MySQL 4.0.2. The CHAR conversion type is available as of 4.0.6. The USING form of CONVERT() is available as of 4.1.0. CAST() and CONVERT(... USING ...) are standard SQL syntax. The non-USING form of CONVERT() is ODBC syntax. CONVERT() with USING is used to convert data between different character sets. In MySQL, transcoding names are the same as the corresponding character set names. For example, this statement converts the string 'abc' in the server's default character set to the corresponding string in the utf8 character set: SELECT CONVERT('abc' USING utf8); The cast functions are useful when you want to create a column with a specific type in a CREATE ... SELECT statement: SELECT enum_col FROM tbl_name ORDER BY CAST(enum_col AS CHAR);  
300 SOUNDS LIKE 23 expr1 SOUNDS LIKE expr2 This is the same as SOUNDEX(expr1) = SOUNDEX(expr2). It is available only in MySQL 4.1 or later.    
301 PERIOD_DIFF 14 PERIOD_DIFF(P1,P2) Returns the number of months between periods P1 and P2. P1 and P2 should be in the format YYMM or YYYYMM. Note that the period arguments P1 and P2 are /not/ date values. mysql> SELECT PERIOD_DIFF(9802,199703); -> 11  
302 LIKE 23 expr LIKE pat [ESCAPE 'escape-char'] Pattern matching using SQL simple regular expression comparison. Returns 1 (TRUE) or 0 (FALSE). If either expr or pat is NULL, the result is NULL. The pattern need not be a literal string. For example, it can be specified as a string expression or table column. With LIKE you can use the following two wildcard characters in the pattern: Character Description % Matches any number of characters, even zero characters _ Matches exactly one character mysql> SELECT 'David!' LIKE 'David_'; -> 1 mysql> SELECT 'David!' LIKE '%D%v%'; -> 1  
303 MULTIPOINT 2 MultiPoint(pt1,pt2,...) Constructs a WKB MultiPoint value using WKB Point arguments. If any argument is not a WKB Point, the return value is NULL.    
304 >> 27 >> Shifts a longlong (BIGINT) number to the right. mysql> SELECT 4 >> 2; -> 1  
305 TRUE FALSE 22 TRUE and FALSE added as alias for 1 and 0, respectively.    
306 AVG 12 AVG([DISTINCT] expr) Returns the average value of expr. The DISTINCT option can be used as of MySQL 5.0.3 to return the averge of the distinct values of expr. mysql> SELECT student_name, AVG(test_score) -> FROM student -> GROUP BY student_name;  
307 MBRWITHIN 8 MBRWithin(g1,g2) Returns 1 or 0 to indicate whether or not the Minimum Bounding Rectangle of g1 is within the Minimum Bounding Rectangle of g2. mysql> SET @g1 = GeomFromText('Polygon((0 0,0 3,3 3,3 0,0 0))'); mysql> SET @g2 = GeomFromText('Polygon((0 0,0 5,5 5,5 0,0 0))'); mysql> SELECT MBRWithin(@g1,@g2), MBRWithin(@g2,@g1); +--------------------+--------------------+ | MBRWithin(@g1,@g2) | MBRWithin(@g2,@g1) | +--------------------+--------------------+ | 1 | 0 | +--------------------+--------------------+  
308 IN 26 expr IN (value,...) Returns 1 if expr is any of the values in the IN list, else returns 0. If all values are constants, they are evaluated according to the type of expr and sorted. The search for the item then is done using a binary search. This means IN is very quick if the IN value list consists entirely of constants. If expr is a case-sensitive string expression, the string comparison is performed in case-sensitive fashion. mysql> SELECT 2 IN (0,3,5,'wefwf'); -> 0 mysql> SELECT 'wefwf' IN (0,3,5,'wefwf'); -> 1  
309 QUOTE 23 QUOTE(str) Quotes a string to produce a result that can be used as a properly escaped data value in an SQL statement. The string is returned surrounded by single quotes and with each instance of single quote ('''), backslash ('\'), ASCII NUL, and Control-Z preceded by a backslash. If the argument is NULL, the return value is the word ``NULL'' without surrounding single quotes. The QUOTE() function was added in MySQL 4.0.3. mysql> SELECT QUOTE('Don\'t!'); -> 'Don\'t!' mysql> SELECT QUOTE(NULL); -> NULL  
310 SESSION_USER 25 SESSION_USER() SESSION_USER() is a synonym for USER().    
311 QUARTER 14 QUARTER(date) Returns the quarter of the year for date, in the range 1 to 4. mysql> SELECT QUARTER('98-04-01'); -> 2  
312 POSITION 23 POSITION(substr IN str) POSITION(substr IN str) is a synonym for LOCATE(substr,str). mysql> SELECT LOCATE('bar', 'foobarbar'); -> 4 mysql> SELECT LOCATE('xbar', 'foobar'); -> 0 mysql> SELECT LOCATE('bar', 'foobarbar',5); -> 7  
313 IS_USED_LOCK 21 IS_USED_LOCK(str) Checks whether the lock named str is in use (that is, locked). If so, it returns the connection identifier of the client that holds the lock. Otherwise, it returns NULL.    
314 POLYFROMTEXT 3 PolyFromText(wkt[,srid]) PolygonFromText(wkt[,srid]) Constructs a POLYGON value using its WKT representation and SRID.    
315 DES_ENCRYPT 17 DES_ENCRYPT(str[,(key_num|key_str)]) Encrypts the string with the given key using the Triple-DES algorithm. On error, this function returns NULL. Note that this function works only if MySQL has been configured with SSL support. See also : [Secure connections]. The encryption key to use is chosen based on the second argument to DES_ENCRYPT(), if one was given: Argument Description No argument The first key from the DES key file is used. key_num The given key number (0-9) from the DES key file is used. key_str The given key string is used to encrypt str. The key file can be specified with the --des-key-file server option. The return string is a binary string where the first character is CHAR(128 | key_num). The 128 is added to make it easier to recognize an encrypted key. If you use a string key, key_num is 127. The string length for the result is new_len = orig_len + (8-(orig_len % 8))+1. key_num des_key_str  
316 LENGTH 23 LENGTH(str) Returns the length of the string str, measured in bytes. A multi-byte character counts as multiple bytes. This means that for a string containing five two-byte characters, LENGTH() returns 10, whereas CHAR_LENGTH() returns 5. mysql> SELECT LENGTH('text'); -> 4  
317 DISTANCE 11 Distance(g1,g2) Returns as a double-precision number the shortest distance between any two points in the two geometries.    
318 STR_TO_DATE 14 STR_TO_DATE(str,format) This is the reverse function of the DATE_FORMAT() function. It takes a string str and a format string format. STR_TO_DATE() returns a DATETIME value if the format string contains both date and time parts, or a DATE or TIME value if the string contains only date or time parts. The date, time, or datetime values contained in str should be given in the format indicated by format. For the specifiers that can be used in format, see the table in the DATE_FORMAT() function description. All other characters are just taken verbatim, thus not being interpreted. If str contains an illegal date, time, or datetime value, STR_TO_DATE() returns NULL. Starting from MySQL 5.0.3, an illegal value also produces a warning. @c next example commented out until format string becomes optional @c mysql> SELECT STR_TO_DATE('2003-10-03'); @c -> 2003-10-03 00:00:00 mysql> SELECT STR_TO_DATE('03.10.2003 09.20', -> '%d.%m.%Y %H.%i'); -> '2003-10-03 09:20:00' mysql> SELECT STR_TO_DATE('10arp', '%carp'); -> '0000-10-00 00:00:00' mysql> SELECT STR_TO_DATE('2003-15-10 00:00:00', -> '%Y-%m-%d %H:%i:%s'); -> NULL  
319 Y 16 Y(p) Returns the Y-coordinate value for the point p as a double-precision number. mysql> SELECT Y(GeomFromText('Point(56.7 53.34)')); +--------------------------------------+ | Y(GeomFromText('Point(56.7 53.34)')) | +--------------------------------------+ | 53.34 | +--------------------------------------+  
320 NUMINTERIORRINGS 0 NumInteriorRings(poly) Returns the number of interior rings in the Polygon value poly. mysql> SET @poly = -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'; mysql> SELECT NumInteriorRings(GeomFromText(@poly)); +---------------------------------------+ | NumInteriorRings(GeomFromText(@poly)) | +---------------------------------------+ | 1 | +---------------------------------------+  
321 INTERIORRINGN 0 InteriorRingN(poly,n) Returns the n-th interior ring for the Polygon value poly as a LineString. Ring numbers begin at 1. mysql> SET @poly = -> 'Polygon((0 0,0 3,3 3,3 0,0 0),(1 1,1 2,2 2,2 1,1 1))'; mysql> SELECT AsText(InteriorRingN(GeomFromText(@poly),1)); +----------------------------------------------+ | AsText(InteriorRingN(GeomFromText(@poly),1)) | +----------------------------------------------+ | LINESTRING(1 1,1 2,2 2,2 1,1 1) | +----------------------------------------------+  
322 UTC_TIME 14 UTC_TIME UTC_TIME() Returns the current UTC time as a value in 'HH:MM:SS' or HHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT UTC_TIME(), UTC_TIME() + 0; -> '18:07:53', 180753  
323 STDDEV 12 STD(expr) STDDEV(expr) Returns the population standard deviation of expr. This is an extension to standard SQL. The STDDEV() form of this function is provided for Oracle compatibility. As of MySQL 5.0.3, the standard SQL function STDDEV_POP() can be used instead.    
324 PERIOD_ADD 14 PERIOD_ADD(P,N) Adds N months to period P (in the format YYMM or YYYYMM). Returns a value in the format YYYYMM. Note that the period argument P is /not/ a date value. mysql> SELECT PERIOD_ADD(9801,2); -> 199803  
325 | 27 | Bitwise OR: mysql> SELECT 29 | 15; -> 31  
326 GEOMFROMTEXT 3 GeomFromText(wkt[,srid]) GeometryFromText(wkt[,srid]) Constructs a geometry value of any type using its WKT representation and SRID.    
327 RIGHT 23 RIGHT(str,len) Returns the rightmost len characters from the string str. mysql> SELECT RIGHT('foobarbar', 4); -> 'rbar'  
328 DATEDIFF 14 DATEDIFF(expr,expr2) DATEDIFF() returns the number of days between the start date expr and the end date expr2. expr and expr2 are date or date-and-time expressions. Only the date parts of the values are used in the calculation. mysql> SELECT DATEDIFF('1997-12-31 23:59:59','1997-12-30'); -> 1 mysql> SELECT DATEDIFF('1997-11-30 23:59:59','1997-12-31'); -> -31  
329 BIN 23 BIN(N) Returns a string representation of the binary value of N, where N is a longlong (BIGINT) number. This is equivalent to CONV(N,10,2). Returns NULL if N is NULL. mysql> SELECT BIN(12); -> '1100'  
330 MULTILINESTRING 2 MultiLineString(ls1,ls2,...) Constructs a WKB MultiLineString value using WKB LineString arguments. If any argument is not a WKB LineString, the return value is NULL.    
331 LOAD DATA 6 The LOAD DATA INFILE statement reads rows from a text file into a table at a very high speed. For more information about the efficiency of INSERT versus LOAD DATA INFILE and speeding up LOAD DATA INFILE, [Insert speed]. As of MySQL 4.1, the character set indicated by the character_set_database system variable is used to interpret the information in the file. SET NAMES and the setting of character_set_client do not affect input interpretation. You can also load data files by using the mysqlimport utility; it operates by sending a LOAD DATA INFILE statement to the server. The --local option causes mysqlimport to read data files from the client host. You can specify the --compress option to get better performance over slow networks if the client and server support the compressed protocol. See also : [mysqlimport, , mysqlimport]. If you specify the LOW_PRIORITY keyword, execution of the LOAD DATA statement is delayed until no other clients are reading from the table. If you specify the CONCURRENT keyword with a MyISAM table that satisfies the condition for concurrent inserts (that is, it contains no free blocks in the middle), then other threads can retrieve data from the table while LOAD DATA is executing. Using this option affects the performance of LOAD DATA a bit, even if no other thread is using the table at the same time. If the LOCAL keyword is specified, it is interpreted with respect to the client end of the connection: --- If LOCAL is specified, the file is read by the client program on the client host and sent to the server. The file can be given as a full pathname to specify its exact location. If given as a relative pathname, the name is interpreted relative to the directory in which the client program was started. --- If LOCAL is not specified, the file must be located on the server host and is read directly by the server. LOCAL is available in MySQL 3.22.6 or later. When locating files on the server host, the server uses the following rules: --- If an absolute pathname is given, the server uses the pathname as is. --- If a relative pathname with one or more leading components is given, the server searches for the file relative to the server's data directory. --- If a filename with no leading components is given, the server looks for the file in the database directory of the default database. Note that these rules mean that a file named as *./myfile.txt is read from the server's data directory, whereas the same file named as *myfile.txt is read from the database directory of the default database. For example, the following LOAD DATA statement reads the file *data.txt from the database directory for db1 because db1 is the current database, even though the statement explicitly loads the file into a table in the db2 database: mysql> USE db1; mysql> LOAD DATA INFILE 'data.txt' INTO TABLE db2.my_table; Note that Windows pathnames are specified using forward slashes rather than backslashes. If you do use backslashes, you must double them. For security reasons, when reading text files located on the server, the files must either reside in the database directory or be readable by all. Also, to use LOAD DATA INFILE on server files, you must have the FILE privilege. LOAD DATA [LOW_PRIORITY | CONCURRENT] [LOCAL] INFILE 'file_name.txt' [REPLACE | IGNORE] INTO TABLE tbl_name [FIELDS [TERMINATED BY '\t'] [[OPTIONALLY] ENCLOSED BY ''] [ESCAPED BY '\\' ] ] [LINES [STARTING BY ''] [TERMINATED BY '\n'] ] [IGNORE number LINES] [(col_name,...)]  
332 BLOB TYPE 1 BLOB[(M)] A BLOB column with a maximum length of 65,535 (2^16 - 1) bytes. Beginning with MySQL 4.1, an optional length M can be given. MySQL will create the column as the smallest BLOB type largest enough to hold values M bytes long.    
333 LOCALTIME 14 LOCALTIME LOCALTIME() LOCALTIME and LOCALTIME() are synonyms for NOW().    
334 MPOINTFROMTEXT 3 MPointFromText(wkt[,srid]) MultiPointFromText(wkt[,srid]) Constructs a MULTIPOINT value using its WKT representation and SRID.    
335 BLOB 1 A BLOB is a binary large object that can hold a variable amount of data. The four BLOB types, TINYBLOB, BLOB, MEDIUMBLOB, and LONGBLOB, differ only in the maximum length of the values they can hold.    
336 PASSWORD 17   mysql> SELECT PASSWORD('badpwd'); -> '7f84554057dd964b'  
337 CHAR 1 [NATIONAL] CHAR(M) [BINARY | ASCII | UNICODE] A fixed-length string that is always right-padded with spaces to the specified length when stored. M represents the column length. The range of M is 0 to 255 characters (1 to 255 prior to MySQL 3.23). Note: Trailing spaces are removed when CHAR values are retrieved. From MySQL 4.1.0 to 5.0.2, a CHAR column with a length specification greater than 255 is converted to the smallest TEXT type that can hold values of the given length. For example, CHAR(500) is converted to TEXT, and CHAR(200000) is converted to MEDIUMTEXT. This is a compatibility feature. However, this conversion causes the column to become a variable-length column, and also affects trailing-space removal. CHAR is shorthand for CHARACTER. NATIONAL CHAR (or its equivalent short form, NCHAR) is the standard SQL way to define that a CHAR column should use the default character set. This is the default in MySQL. As of MySQL 4.1.2, the BINARY attribute is shorthand for specifying the binary collation of the column character set. Sorting and comparison is based on numeric character values. Before 4.1.2, BINARY attribute causes the column to be treated as a binary string. Sorting and comparison is based on numeric byte values. From MySQL 4.1.0 on, column type CHAR BYTE is an alias for CHAR BINARY. This is a compatibility feature. From MySQL 4.1.0 on, the ASCII attribute can be specified for CHAR. It assigns the latin1 character set. From MySQL 4.1.1 on, the UNICODE attribute can be specified for CHAR. It assigns the ucs2 character set. MySQL allows you to create a column of type CHAR(0). This is mainly useful when you have to be compliant with some old applications that depend on the existence of a column but that do not actually use the value. This is also quite nice when you need a column that can take only two values: A CHAR(0) column that is not defined as NOT NULL occupies only one bit and can take only the values NULL and '' (the empty string). CHAR This is a synonym for CHAR(1).    
338 UTC_DATE 14 UTC_DATE UTC_DATE() Returns the current UTC date as a value in 'YYYY-MM-DD' or YYYYMMDD format, depending on whether the function is used in a string or numeric context. mysql> SELECT UTC_DATE(), UTC_DATE() + 0; -> '2003-08-14', 20030814  
339 DIMENSION 19 Dimension(g) Returns the inherent dimension of the geometry value g. The result can be -1, 0, 1, or 2. (The meaning of these values is given in [GIS class geometry].) mysql> SELECT Dimension(GeomFromText('LineString(1 1,2 2)')); +------------------------------------------------+ | Dimension(GeomFromText('LineString(1 1,2 2)')) | +------------------------------------------------+ | 1 | +------------------------------------------------+  
340 COUNT DISTINCT 12 COUNT(DISTINCT expr,[expr...]) Returns a count of the number of different non-NULL values. mysql> SELECT COUNT(DISTINCT results) FROM student;  
341 BIT 1 BIT[(M)] A bit-field type. M indicates the number of bits per value, from 1 to 64. The default is 1 if M is omitted. This data type was added in MySQL 5.0.3 for MyISAM, and extended in 5.0.5 to MEMORY, InnoDB, and BDB. Before 5.0.3, BIT is a synonym for TINYINT(1).    
342 EQUALS 11 Equals(g1,g2) Returns 1 or 0 to indicate whether or not g1 is spatially equal to g2.    
343 SHOW CREATE VIEW 24 This statement shows a CREATE VIEW statement that creates the given view. SHOW CREATE VIEW view_name  
344 INTERVAL 26 INTERVAL(N,N1,N2,N3,...) Returns 0 if N < N1, 1 if N < N2 and so on or -1 if N is NULL. All arguments are treated as integers. It is required that N1 < N2 < N3 < ... < Nn for this function to work correctly. This is because a binary search is used (very fast). mysql> SELECT INTERVAL(23, 1, 15, 17, 30, 44, 200); -> 3 mysql> SELECT INTERVAL(10, 1, 10, 100, 1000); -> 2 mysql> SELECT INTERVAL(22, 23, 30, 44, 200); -> 0  
345 FROM_DAYS 14 FROM_DAYS(N) Given a daynumber N, returns a DATE value. mysql> SELECT FROM_DAYS(729669); -> '1997-10-07'  
346 BIT_COUNT 27 BIT_COUNT(N) Returns the number of bits that are set in the argument N. mysql> SELECT BIT_COUNT(29); -> 4  
347 UTC_TIMESTAMP 14 UTC_TIMESTAMP UTC_TIMESTAMP() Returns the current UTC date and time as a value in 'YYYY-MM-DD HH:MM:SS' or YYYYMMDDHHMMSS format, depending on whether the function is used in a string or numeric context. mysql> SELECT UTC_TIMESTAMP(), UTC_TIMESTAMP() + 0; -> '2003-08-14 18:08:04', 20030814180804  
348 + 4 + Addition: mysql> SELECT 3+5; -> 8  
349 INET_NTOA 21 INET_NTOA(expr) Given a numeric network address (4 or 8 byte), returns the dotted-quad representation of the address as a string. mysql> SELECT INET_NTOA(3520061480); -> '209.207.224.40'  
350 ACOS 4 ACOS(X) Returns the arc cosine of X, that is, the value whose cosine is X. Returns NULL if X is not in the range -1 to 1. mysql> SELECT ACOS(1); -> 0.000000 mysql> SELECT ACOS(1.0001); -> NULL mysql> SELECT ACOS(0); -> 1.570796  
351 ISOLATION 10 SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE } This statement sets the transaction isolation level for the next transaction, globally, or for the current session. The default behavior of SET TRANSACTION is to set the isolation level for the next (not yet started) transaction. If you use the GLOBAL keyword, the statement sets the default transaction level globally for all new connections created from that point on. Existing connections are unaffected. You need the SUPER privilege to do this. Using the SESSION keyword sets the default transaction level for all future transactions performed on the current connection. For descriptions of each InnoDB transaction isolation level, see [InnoDB transaction isolation, InnoDB transaction isolation]. InnoDB supports each of these levels from MySQL 4.0.5 on. The default level is REPEATABLE READ. You can set the initial default global isolation level for mysqld with the --transaction-isolation option. See also : [Server options].    
352 CEILING 4 CEILING(X) CEIL(X) Returns the smallest integer value not less than X. mysql> SELECT CEILING(1.23); -> 2 mysql> SELECT CEIL(-1.23); -> -1  
353 SIN 4 SIN(X) Returns the sine of X, where X is given in radians. mysql> SELECT SIN(PI()); -> 0.000000  
354 DAYOFWEEK 14 DAYOFWEEK(date) Returns the weekday index for date (1 = Sunday, 2 = Monday, ..., 7 = Saturday). These index values correspond to the ODBC standard. mysql> SELECT DAYOFWEEK('1998-02-03'); -> 3  
355 LINEFROMWKB 13 LineFromWKB(wkb[,srid]) LineStringFromWKB(wkb[,srid]) Constructs a LINESTRING value using its WKB representation and SRID.    
356 GEOMETRYTYPE 19 GeometryType(g) Returns as a string the name of the geometry type of which the geometry instance g is a member. The name corresponds to one of the instantiable Geometry subclasses. mysql> SELECT GeometryType(GeomFromText('POINT(1 1)')); +------------------------------------------+ | GeometryType(GeomFromText('POINT(1 1)')) | +------------------------------------------+ | POINT | +------------------------------------------+  
357 GRANT TYPES 7 For the GRANT and REVOKE statements, priv_type can be specified as any of the following: Privilege Meaning ALL [PRIVILEGES] Sets all simple privileges except GRANT OPTION ALTER Allows use of ALTER TABLE ALTER ROUTINE Alter or drop stored routines CREATE Allows use of CREATE TABLE CREATE ROUTINE Create stored routines CREATE TEMPORARY TABLES Allows use of CREATE TEMPORARY TABLE CREATE USER Allows use of CREATE USER, DROP USER, RENAME USER, and REVOKE ALL PRIVILEGES. CREATE VIEW Allows use of CREATE VIEW DELETE Allows use of DELETE DROP Allows use of DROP TABLE EXECUTE Allows the user to run stored routines FILE Allows use of SELECT ... INTO OUTFILE and LOAD DATA INFILE INDEX Allows use of CREATE INDEX and DROP INDEX INSERT Allows use of INSERT LOCK TABLES Allows use of LOCK TABLES on tables for which you have the SELECT privilege PROCESS Allows use of SHOW FULL PROCESSLIST REFERENCES Not implemented RELOAD Allows use of FLUSH REPLICATION CLIENT Allows the user to ask where slave or master servers are REPLICATION SLAVE Needed for replication slaves (to read binary log events from the master) SELECT Allows use of SELECT SHOW DATABASES SHOW DATABASES shows all databases SHOW VIEW Allows use of SHOW CREATE VIEW SHUTDOWN Allows use of mysqladmin shutdown SUPER Allows use of CHANGE MASTER, KILL, PURGE MASTER LOGS, and SET GLOBAL statements, the mysqladmin debug command; allows you to connect (once) even if max_connections is reached UPDATE Allows use of UPDATE USAGE Synonym for ``no privileges'' GRANT OPTION Allows privileges to be granted    
358 CREATE VIEW 24 This statement creates a new view, or replaces an existing one if the OR REPLACE clause is given. The select_statement is a SELECT statement that provides the definition of the view. The statement can select from base tables or other views. This statement requires the CREATE VIEW privilege for the view, and some privilege for each column selected by the SELECT statement. For columns used elsewhere in the SELECT statement you must have the SELECT privilege. If the OR REPLACE clause is present, you must also have the DELETE privilege for the view. A view belongs to a database. By default, a new view is created in the current database. To create the view explicitly in a given database, specify the name as db_name.view_name when you create it. mysql> CREATE VIEW test.v AS SELECT * FROM t; Tables and views share the same namespace within a database, so a database cannot contain a table and a view that have the same name. Views must have unique column names with no duplicates, just like base tables. By default, the names of the columns retrieved by the SELECT statement are used for the view column names. To define explicit names for the view columns, the optional column_list clause can be given as a list of comma-separated identifiers. The number of names in column_list must be the same as the number of columns retrieved by the SELECT statement. Columns retrieved by the SELECT statement can be simple references to table columns. They can also be expressions that use functions, constant values, operators, and so forth. Unqualified table or view names in the SELECT statement are interpreted with respect to the default database. A view can refer to tables or views in other databases by qualifying the table or view name with the proper database name. A view can be created from many kinds of SELECT statements. It can refer to base tables or other views. It can use joins, UNION, and subqueries. The SELECT need not even refer to any tables. The following example defines a view that selects two columns from another table, as well as an expression calculated from those columns: mysql> CREATE TABLE t (qty INT, price INT); mysql> INSERT INTO t VALUES(3, 50); mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t; mysql> SELECT * FROM v; +------+-------+-------+ | qty | price | value | +------+-------+-------+ | 3 | 50 | 150 | +------+-------+-------+ A view definition is subject to the following restrictions: --- The SELECT statement cannot contain a subquery in the FROM clause. --- The SELECT statement cannot refer to system or user variables. --- The SELECT statement cannot refer to prepared statement parameters. --- Within a stored routine, the definition cannot refer to routine parameters or local variables. --- Any table or view referred to in the definition must exist. However, after a view has been created, it is possible to drop a table or view that the definition refers to. To check a view definition for problems of this kind, use the CHECK TABLE statement. --- The definition cannot refer to a TEMPORARY table, and you cannot create a TEMPORARY view. --- The tables named in the view definition must already exist. --- You cannot associate a trigger with a view. ORDER BY is allowed in a view definition, but it is ignored if you select from a view using a statement that has its own ORDER BY. For other options or clauses in the definition, they are added to the options or clauses of the statement that references the view, but the effect is undefined. For example, if a view definition includes a LIMIT clause, and you select from the view using a statement that has its own LIMIT clause, it is undefined which limit applies. This same principle applies to options such as ALL, DISTINCT, or SQL_SMALL_RESULT that follow the SELECT keyword, and to clauses such as INTO, FOR UPDATE, LOCK IN SHARE MODE, and PROCEDURE. If you create a view and then change the query processing environment by changing system variables, that may affect the results you get from the view: mysql> CREATE VIEW v AS SELECT CHARSET(CHAR(65)), COLLATION(CHAR(65)); Query OK, 0 rows affected (0.00 sec) mysql> SET NAMES 'latin1'; Query OK, 0 rows affected (0.00 sec) mysql> SELECT * FROM v; +-------------------+---------------------+ | CHARSET(CHAR(65)) | COLLATION(CHAR(65)) | +-------------------+---------------------+ | latin1 | latin1_swedish_ci | +-------------------+---------------------+ 1 row in set (0.00 sec) mysql> SET NAMES 'utf8'; Query OK, 0 rows affected (0.00 sec) mysql> SELECT * FROM v; +-------------------+---------------------+ | CHARSET(CHAR(65)) | COLLATION(CHAR(65)) | +-------------------+---------------------+ | utf8 | utf8_general_ci | +-------------------+---------------------+ 1 row in set (0.00 sec) The optional ALGORITHM clause is a MySQL extension to standard SQL. ALGORITHM takes three values: MERGE, TEMPTABLE, or UNDEFINED. The default algorithm is UNDEFINED if no ALGORITHM clause is present. The algorithm affects how MySQL processes the view. For MERGE, the text of a statement that refers to the view and the view definition are merged such that parts of the view definition replace corresponding parts of the statement. For TEMPTABLE, the results from the view are retrieved into a temporary table, which then is used to execute the statement. For UNDEFINED, MySQL chooses which algorithm to use. It prefers MERGE over TEMPTABLE if possible, because MERGE is usually more efficient and because a view cannot be updatable if a temporary table is used. A reason to choose TEMPTABLE explicitly is that locks can be released on underlying tables after the temporary table has been created and before it is used to finish processing the statement. This might result in quicker lock release than the MERGE algorithm so that other clients that use the view are not blocked as long. A view algorithm can be UNDEFINED three ways: --- No ALGORITHM clause is present in the CREATE VIEW statement. --- The CREATE VIEW statement has an explicit ALGORITHM = UNDEFINED clause. --- ALGORITHM = MERGE is specified for a view that can be processed only with a temporary table. In this case, MySQL generates a warning and sets the algorithm to UNDEFINED. As mentioned earlier, MERGE is handled by merging corresponding parts of a view definition into the statement that refers to the view. The following examples briefly illustrate how the MERGE algorithm works. The examples assume that there is a view v_merge that has this definition: CREATE ALGORITHM = MERGE VIEW v_merge (vc1, vc2) AS SELECT c1, c2 FROM t WHERE c3 > 100; Example 1: Suppose that we issue this statement: SELECT * FROM v_merge; MySQL handles the statement as follows: --- v_merge becomes t --- * becomes vc1, vc2, which corresponds to c1, c2 --- The view WHERE clause is added The resulting statement to be executed becomes: SELECT c1, c2 FROM t WHERE c3 > 100; Example 2: Suppose that we issue this statement: SELECT * FROM v_merge WHERE vc1 < 100; This statement is handled similarly to the previous one, except that vc1 < 100 becomes c1 < 100 and the view WHERE clause is added to the statement WHERE clause using an AND connective (and parentheses are added to make sure the parts of the clause are executed with correct precedence). The resulting statement to be executed becomes: SELECT c1, c2 FROM t WHERE (c3 > 100) AND (c1 < 100); Effectively, the statement to be executed has a WHERE clause of this form: WHERE (select WHERE) AND (view WHERE) The MERGE algorithm requires a one-to relationship between the rows in the view and the rows in the underlying table. If this relationship does not hold, a temporary table must be used instead. Lack of a one-to-one relationship occurs if the view contains any of a number of constructs: --- Aggregate functions (SUM(), MIN(), MAX(), COUNT(), and so forth) --- DISTINCT --- GROUP BY --- HAVING --- UNION or UNION ALL --- Refers only to literal values (in this case, there is no underlying table) Some views are updatable. That is, you can use them in statements such as UPDATE, DELETE, or INSERT to update the contents of the underlying table. For a view to be updatable, there must be a one-to relationship between the rows in the view and the rows in the underlying table. There are also certain other constructs that make a view non-updatable. To be more specific, a view is not updatable if it contains any of the following: --- Aggregate functions (SUM(), MIN(), MAX(), COUNT(), and so forth) --- DISTINCT --- GROUP BY --- HAVING --- UNION or UNION ALL --- Subquery in the select list --- Join --- Non-updatable view in the FROM clause --- A subquery in the WHERE clause that refers to a table in the FROM clause --- Refers only to literal values (in this case, there is no underlying table to update) --- ALGORITHM = TEMPTABLE (use of a temporary table always makes a view non-updatable) With respect to insertability (being updatable with INSERT statements), an updatable view is insertable if it also satisfies these additional requirements for the view columns: --- There must be no duplicate view column names. --- The view must contain all columns in the base table that do not have a default value. --- The view columns must be simple column references and not derived columns. A derived column is one that is not a simple column reference but is derived from an expression. These are examples of derived columns: 3.14159 col1 + 3 UPPER(col2) col3 / col4 (subquery) A view that has a mix of simple column references and derived columns is not insertable, but it can be updatable if you update only those columns that are not derived. Consider this view: CREATE VIEW v AS SELECT col1, 1 AS col2 FROM t; This view is not insertable because col2 is derived from an expression. But it is updatable if the update does not try to update col2. This update is allowable: UPDATE v SET col1 = 0; This update is not allowable because it attempts to update a derived column: UPDATE v SET col2 = 0; It is sometimes possible for a multiple-table view to be updatable, assuming that it can be processed with the MERGE algorithm. For this to work, the view must use an inner join (not an outer join or a UNION). Also, only a single table in the view definition can be updated, so the SET clause must name only columns from one of the tables in the view. Views that use UNION ALL are disallowed even though they might be theoretically updatable, because the implementation uses temporary tables to process them. For a multiple-table updatable view, INSERT can work if it inserts into a single table. DELETE is not supported. The WITH CHECK OPTION clause can be given for an updatable view to prevent inserts or updates to rows except those for which the WHERE clause in the select_statement is true.    
359 TRIM 23 TRIM([{BOTH | LEADING | TRAILING} [remstr] FROM] str) TRIM(remstr FROM] str) Returns the string str with all remstr prefixes and/or suffixes removed. If none of the specifiers BOTH, LEADING, or TRAILING is given, BOTH is assumed. If remstr is optional and not specified, spaces are removed. mysql> SELECT TRIM(' bar '); -> 'bar' mysql> SELECT TRIM(LEADING 'x' FROM 'xxxbarxxx'); -> 'barxxx' mysql> SELECT TRIM(BOTH 'x' FROM 'xxxbarxxx'); -> 'bar' mysql> SELECT TRIM(TRAILING 'xyz' FROM 'barxxyz'); -> 'barx'  
360 IS 26 IS boolean_value IS NOT boolean_value Tests whether a value against a boolean value, where boolean_value can be TRUE, FALSE, or UNKNOWN. mysql> SELECT 1 IS TRUE, 0 IS FALSE, NULL IS UNKNOWN; -> 1, 1, 1 mysql> SELECT 1 IS NOT UNKNOWN, 0 IS NOT UNKNOWN, NULL IS NOT UNKNOWN; -> 1, 1, 0  
361 GET_FORMAT 14 GET_FORMAT(DATE|TIME|DATETIME, 'EUR'|'USA'|'JIS'|'ISO'|'INTERNAL') Returns a format string. This function is useful in combination with the DATE_FORMAT() and the STR_TO_DATE() functions. The three possible values for the first argument and the five possible values for the second argument result in 15 possible format strings (for the specifiers used, see the table in the DATE_FORMAT() function description). Function Call Result GET_FORMAT(DATE,'USA') '%m.%d.%Y' GET_FORMAT(DATE,'JIS') '%Y-%m-%d' GET_FORMAT(DATE,'ISO') '%Y-%m-%d' GET_FORMAT(DATE,'EUR') '%d.%m.%Y' GET_FORMAT(DATE,'INTERNAL') '%Y%m%d' GET_FORMAT(DATETIME,'USA') '%Y-%m-%d-%H.%i.%s' GET_FORMAT(DATETIME,'JIS') '%Y-%m-%d %H:%i:%s' GET_FORMAT(DATETIME,'ISO') '%Y-%m-%d %H:%i:%s' GET_FORMAT(DATETIME,'EUR') '%Y-%m-%d-%H.%i.%s' GET_FORMAT(DATETIME,'INTERNAL') '%Y%m%d%H%i%s' GET_FORMAT(TIME,'USA') '%h:%i:%s %p' GET_FORMAT(TIME,'JIS') '%H:%i:%s' GET_FORMAT(TIME,'ISO') '%H:%i:%s' GET_FORMAT(TIME,'EUR') '%H.%i.%S' GET_FORMAT(TIME,'INTERNAL') '%H%i%s' ISO format is ISO 9075, not ISO 8601. As of MySQL 4.1.4, TIMESTAMP can also be used; GET_FORMAT() returns the same values as for DATETIME. mysql> SELECT DATE_FORMAT('2003-10-03',GET_FORMAT(DATE,'EUR')); -> '03.10.2003' mysql> SELECT STR_TO_DATE('10.31.2003',GET_FORMAT(DATE,'USA')); -> 2003-10-31 @c Following is commented out because not yet implemented @c mysql> SET DATE_FORMAT=GET_FORMAT(DATE, 'USA'); SELECT '2003-10-31'; @c -> 10-31-2003  
362 TINYBLOB 1 TINYBLOB A BLOB column with a maximum length of 255 (2^8 - 1) bytes.    
363 SAVEPOINT 10 SAVEPOINT identifier ROLLBACK TO SAVEPOINT identifier Starting from MySQL 4.0.14 and 4.1.1, InnoDB supports the SQL statements SAVEPOINT and ROLLBACK TO SAVEPOINT.    
364 IF 9 IF(expr1,expr2,expr3) If expr1 is TRUE (expr1 <> 0 and expr1 <> NULL) then IF() returns expr2, else it returns expr3. IF() returns a numeric or string value, depending on the context in which it is used. mysql> SELECT IF(1>2,2,3); -> 3 mysql> SELECT IF(1<2,'yes','no'); -> 'yes' mysql> SELECT IF(STRCMP('test','test1'),'no','yes'); -> 'no'  
365 PURGE 6   PURGE MASTER LOGS TO 'mysql-bin.010'; PURGE MASTER LOGS BEFORE '2003-04-02 22:46:26';  
366 USER 25 USER() Returns the current MySQL username and hostname. mysql> SELECT USER(); -> 'davida@localhost'  
367 MPOINTFROMWKB 13 MPointFromWKB(wkb[,srid]) MultiPointFromWKB(wkb[,srid]) Constructs a MULTIPOINT value using its WKB representation and SRID.    
368 ALTER TABLE 28 ALTER TABLE allows you to change the structure of an existing table. For example, you can add or delete columns, create or destroy indexes, change the type of existing columns, or rename columns or the table itself. You can also change the comment for the table and type of the table. ALTER [IGNORE] TABLE tbl_name alter_specification [, alter_specification] ... alter_specification: ADD [COLUMN] column_definition [FIRST | AFTER col_name ] | ADD [COLUMN] (column_definition,...) | ADD INDEX [index_name] [index_type] (index_col_name,...) | ADD [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name,...) | ADD [CONSTRAINT [symbol]] UNIQUE [index_name] [index_type] (index_col_name,...) | ADD [FULLTEXT|SPATIAL] [index_name] (index_col_name,...) | ADD [CONSTRAINT [symbol]] FOREIGN KEY [index_name] (index_col_name,...) [reference_definition] | ALTER [COLUMN] col_name {SET DEFAULT literal | DROP DEFAULT} | CHANGE [COLUMN] old_col_name column_definition [FIRST|AFTER col_name] | MODIFY [COLUMN] column_definition [FIRST | AFTER col_name] | DROP [COLUMN] col_name | DROP PRIMARY KEY | DROP INDEX index_name | DROP FOREIGN KEY fk_symbol | DISABLE KEYS | ENABLE KEYS | RENAME [TO] new_tbl_name | ORDER BY col_name | CONVERT TO CHARACTER SET charset_name [COLLATE collation_name] | [DEFAULT] CHARACTER SET charset_name [COLLATE collation_name] | DISCARD TABLESPACE | IMPORT TABLESPACE | table_options  
369 CHAR BYTE 22 CHAR BYTE is an alias for CHAR BINARY.    
370 MERGE 7 @menu * MERGE table problems:: MERGE Table Problems @end menu The MERGE storage engine was introduced in MySQL 3.23.25. It is also known as the MRG_MyISAM engine. A MERGE table is a collection of identical MyISAM tables that can be used as one. ``Identical'' means that all tables have identical column and index information. You can't merge tables in which the columns are listed in a different order, don't have exactly the same columns, or have the indexes in different order. However, any or all of the tables can be compressed with myisampack. See also : [myisampack, , myisampack]. Differences in table options such as AVG_ROW_LENGTH, MAX_ROWS, or PACK_KEYS do not matter. mysql> CREATE TABLE t1 ( -> a INT NOT NULL AUTO_INCREMENT PRIMARY KEY, -> message CHAR(20)); mysql> CREATE TABLE t2 ( -> a INT NOT NULL AUTO_INCREMENT PRIMARY KEY, -> message CHAR(20)); mysql> INSERT INTO t1 (message) VALUES ('Testing'),('table'),('t1'); mysql> INSERT INTO t2 (message) VALUES ('Testing'),('table'),('t2'); mysql> CREATE TABLE total ( -> a INT NOT NULL AUTO_INCREMENT, -> message CHAR(20), INDEX(a)) -> TYPE=MERGE UNION=(t1,t2) INSERT_METHOD=LAST;  
371 CREATE TABLE 28 CREATE TABLE creates a table with the given name. You must have the CREATE privilege for the table. Rules for allowable table names are given in [Legal names]. By default, the table is created in the current database. An error occurs if the table exists, if there is no current database, or if the database does not exist. CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name [(create_definition,...)] [table_options] [select_statement]  
372 > 26 > Greater than: mysql> SELECT 2 > 2; -> 0  
373 MICROSECOND 14 MICROSECOND(expr) Returns the microseconds from the time or datetime expression expr as a number in the range from 0 to 999999. mysql> SELECT MICROSECOND('12:00:00.123456'); -> 123456 mysql> SELECT MICROSECOND('1997-12-31 23:59:59.000010'); -> 10  
374 ANALYZE 7 This statement analyzes and stores the key distribution for a table. During the analysis, the table is locked with a read lock. This works on MyISAM and BDB tables and (as of MySQL 4.0.13) InnoDB tables. For MyISAM tables, this statement is equivalent to using myisamchk -a. MySQL uses the stored key distribution to decide the order in which tables should be joined when you perform a join on something other than a constant. ANALYZE [LOCAL | NO_WRITE_TO_BINLOG] TABLE tbl_name [, tbl_name] ...  
375 CONSTRAINT 7 The syntax of a foreign key constraint definition in InnoDB looks like this: [CONSTRAINT symbol] FOREIGN KEY [id] (index_col_name, ...) REFERENCES tbl_name (index_col_name, ...) [ON DELETE {RESTRICT | CASCADE | SET NULL | NO ACTION}] [ON UPDATE {RESTRICT | CASCADE | SET NULL | NO ACTION}] CREATE TABLE product (category INT NOT NULL, id INT NOT NULL, price DECIMAL, PRIMARY KEY(category, id)) TYPE=INNODB; CREATE TABLE customer (id INT NOT NULL, PRIMARY KEY (id)) TYPE=INNODB; CREATE TABLE product_order (no INT NOT NULL AUTO_INCREMENT, product_category INT NOT NULL, product_id INT NOT NULL, customer_id INT NOT NULL, PRIMARY KEY(no), INDEX (product_category, product_id), FOREIGN KEY (product_category, product_id) REFERENCES product(category, id) ON UPDATE CASCADE ON DELETE RESTRICT, INDEX (customer_id), FOREIGN KEY (customer_id) REFERENCES customer(id)) TYPE=INNODB;  
376 FIELD 23 FIELD(str,str1,str2,str3,...) Returns the index of str in the str1, str2, str3, ... list. Returns 0 if str is not found. If all arguments to FIELD() are strings, all arguments are compared as strings. If all arguments are numbers, they are compared as numbers. Otherwise, the arguments are compared as double. If str is NULL, the return value is 0 because NULL fails equality comparison with any value. FIELD() is the complement of ELT(). mysql> SELECT FIELD('ej', 'Hej', 'ej', 'Heja', 'hej', 'foo'); -> 2 mysql> SELECT FIELD('fo', 'Hej', 'ej', 'Heja', 'hej', 'foo'); -> 0  
377 MAKETIME 14 MAKETIME(hour,minute,second) Returns a time value calculated from the hour, minute, and second arguments. mysql> SELECT MAKETIME(12,15,30); -> '12:15:30'  
378 CURDATE 14 CURDATE() Returns the current date as a value in 'YYYY-MM-DD' or YYYYMMDD format, depending on whether the function is used in a string or numeric context. mysql> SELECT CURDATE(); -> '1997-12-15' mysql> SELECT CURDATE() + 0; -> 19971215  
379 MIN MAX 12 MIN([DISTINCT] expr) MAX([DISTINCT] expr) Returns the minimum or maximum value of expr. MIN() and MAX() may take a string argument; in such cases they return the minimum or maximum string value. See also : [MySQL indexes]. The DISTINCT keyword can be used as of MySQL 5.0.0 to find the minimum or maximum of the distinct values of expr; this is supported, but produces the same result as omitting DISTINCT. mysql> SELECT student_name, MIN(test_score), MAX(test_score) -> FROM student -> GROUP BY student_name;  
380 SET PASSWORD 7   SET PASSWORD = PASSWORD('some password') SET PASSWORD FOR user = PASSWORD('some password')  
381 ENUM 1 ENUM('value1','value2',...) An enumeration. A string object that can have only one value, chosen from the list of values 'value1', 'value2', ..., NULL or the special '' error value. An ENUM column can have a maximum of 65,535 distinct values. ENUM values are represented internally as integers.    
382 DATABASE 25 DATABASE() Returns the default (current) database name. As of MySQL 4.1, the string has the utf8 character set. mysql> SELECT DATABASE(); -> 'test'  
383 POINTFROMWKB 13 PointFromWKB(wkb[,srid]) Constructs a POINT value using its WKB representation and SRID.    
384 POWER 4 POW(X,Y) POWER(X,Y) Returns the value of X raised to the power of Y. mysql> SELECT POW(2,2); -> 4.000000 mysql> SELECT POW(2,-2); -> 0.250000  
385 ATAN 4 ATAN(X) Returns the arc tangent of X, that is, the value whose tangent is X. mysql> SELECT ATAN(2); -> 1.107149 mysql> SELECT ATAN(-2); -> -1.107149  
386 STRCMP 23 STRCMP(expr1,expr2) STRCMP() returns 0 if the strings are the same, -1 if the first argument is smaller than the second according to the current sort order, and 1 otherwise. mysql> SELECT STRCMP('text', 'text2'); -> -1 mysql> SELECT STRCMP('text2', 'text'); -> 1 mysql> SELECT STRCMP('text', 'text'); -> 0  
387 INSERT DELAYED 6 The DELAYED option for the INSERT statement is a MySQL extension to standard SQL that is very useful if you have clients that can't wait for the INSERT to complete. This is a common problem when you use MySQL for logging and you also periodically run SELECT and UPDATE statements that take a long time to complete. DELAYED was introduced in MySQL 3.22.15. When a client uses INSERT DELAYED, it gets an okay from the server at once, and the row is queued to be inserted when the table is not in use by any other thread. Another major benefit of using INSERT DELAYED is that inserts from many clients are bundled together and written in one block. This is much faster than doing many separate inserts. There are some constraints on the use of DELAYED: --- INSERT DELAYED works only with ISAM, MyISAM, and (beginning with MySQL 4.1) MEMORY tables. For MyISAM tables, if there are no free blocks in the middle of the data file, concurrent SELECT and INSERT statements are supported. Under these circumstances, you very seldom need to use INSERT DELAYED with MyISAM. See also : [MyISAM storage engine, , MyISAM storage engine]. See also : [MEMORY storage engine, , MEMORY storage engine]. --- INSERT DELAYED should be used only for INSERT statements that specify value lists. This is enforced as of MySQL 4.0.18. The server ignores DELAYED for INSERT DELAYED ... SELECT statements. --- The server ignores DELAYED for INSERT DELAYED ... ON DUPLICATE UPDATE statements. --- Because the statement returns immediately before the rows are inserted, you cannot use LAST_INSERT_ID() to get the AUTO_INCREMENT value the statement might generate. --- DELAYED rows are not visible to SELECT statements until they actually have been inserted. --- DELAYED are ignored on slaves, because this could cause the slave to have different data than the master. INSERT DELAYED ...  
388 MEDIUMTEXT 1 MEDIUMTEXT A TEXT column with a maximum length of 16,777,215 (2^24 - 1) characters.    
389 LN 4 LN(X) Returns the natural logarithm of X. mysql> SELECT LN(2); -> 0.693147 mysql> SELECT LN(-2); -> NULL  
390 LOG 4 LOG(X) LOG(B,X) If called with one parameter, this function returns the natural logarithm of X. mysql> SELECT LOG(2); -> 0.693147 mysql> SELECT LOG(-2); -> NULL  
391 SET SQL_LOG_BIN 6 SET SQL_LOG_BIN = {0|1} Disables or enables binary logging for the current connection (SQL_LOG_BIN is a session variable) if the client connects using an account that has the SUPER privilege. The statement is refused with an error if the client does not have that privilege. (Before MySQL 4.1.2, the statement was simply ignored in that case.)    
392 != 26 <> != Not equal: mysql> SELECT '.01' <> '0.01'; -> 1 mysql> SELECT .01 <> '0.01'; -> 0 mysql> SELECT 'zapp' <> 'zappp'; -> 1  
393 AES_DECRYPT 17 AES_ENCRYPT(str,key_str) AES_DECRYPT(crypt_str,key_str) These functions allow encryption and decryption of data using the official AES (Advanced Encryption Standard) algorithm, previously known as "Rijndael." Encoding with a 128-bit key length is used, but you can extend it up to 256 bits by modifying the source. We chose 128 bits because it is much faster and it is usually secure enough. The input arguments may be any length. If either argument is NULL, the result of this function is also NULL. Because AES is a block-level algorithm, padding is used to encode uneven length strings and so the result string length may be calculated as 16*(trunc(string_length/16)+1). If AES_DECRYPT() detects invalid data or incorrect padding, it returns NULL. However, it is possible for AES_DECRYPT() to return a non-NULL value (possibly garbage) if the input data or the key is invalid. You can use the AES functions to store data in an encrypted form by modifying your queries: INSERT INTO t VALUES (1,AES_ENCRYPT('text','password'));  
394 DAYNAME 14 DAYNAME(date) Returns the name of the weekday for date. mysql> SELECT DAYNAME('1998-02-05'); -> 'Thursday'  
395 COERCIBILITY 25 COERCIBILITY(str) Returns the collation coercibility value of the string argument. mysql> SELECT COERCIBILITY('abc' COLLATE latin1_swedish_ci); -> 0 mysql> SELECT COERCIBILITY(USER()); -> 3 mysql> SELECT COERCIBILITY('abc'); -> 4  
396 INT 1 INT[(M)] [UNSIGNED] [ZEROFILL] A normal-size integer. The signed range is -2147483648 to 2147483647. The unsigned range is 0 to 4294967295. INTEGER[(M)] [UNSIGNED] [ZEROFILL] This is a synonym for INT.    
397 RLIKE 23 expr REGEXP pat expr RLIKE pat Performs a pattern match of a string expression expr against a pattern pat. The pattern can be an extended regular expression. The syntax for regular expressions is discussed in [Regexp]. Returns 1 if expr matches pat, otherwise returns 0. If either expr or pat is NULL, the result is NULL. RLIKE is a synonym for REGEXP, provided for mSQL compatibility. The pattern need not be a literal string. For example, it can be specified as a string expression or table column. Note: Because MySQL uses the C escape syntax in strings (for example, '\n' to represent newline), you must double any '\' that you use in your REGEXP strings. As of MySQL 3.23.4, REGEXP is not case sensitive for normal (not binary) strings. mysql> SELECT 'Monty!' REGEXP 'm%y%%'; -> 0 mysql> SELECT 'Monty!' REGEXP '.*'; -> 1 mysql> SELECT 'new*\n*line' REGEXP 'new\\*.\\*line'; -> 1 mysql> SELECT 'a' REGEXP 'A', 'a' REGEXP BINARY 'A'; -> 1 0 mysql> SELECT 'a' REGEXP '^[a-d]'; -> 1  
398 GLENGTH 18 GLength(ls) Returns as a double-precision number the length of the LineString value ls in its associated spatial reference. mysql> SET @ls = 'LineString(1 1,2 2,3 3)'; mysql> SELECT GLength(GeomFromText(@ls)); +----------------------------+ | GLength(GeomFromText(@ls)) | +----------------------------+ | 2.8284271247462 | +----------------------------+  
399 RADIANS 4 RADIANS(X) Returns the argument X, converted from degrees to radians. mysql> SELECT RADIANS(90); -> 1.570796  
400 COLLATION 25 COLLATION(str) Returns the collation for the character set of the string argument. mysql> SELECT COLLATION('abc'); -> 'latin1_swedish_ci' mysql> SELECT COLLATION(_utf8'abc'); -> 'utf8_general_ci'  
401 COALESCE 26 COALESCE(value,...) Returns the first non-NULL value in the list. mysql> SELECT COALESCE(NULL,1); -> 1 mysql> SELECT COALESCE(NULL,NULL,NULL); -> NULL  
402 VERSION 25 VERSION() Returns a string that indicates the MySQL server version. As of MySQL 4.1, the string has the utf8 character set. mysql> SELECT VERSION(); -> '4.1.3-beta-log'  
403 MAKE_SET 23 MAKE_SET(bits,str1,str2,...) Returns a set value (a string containing substrings separated by ',' characters) consisting of the strings that have the corresponding bit in bits set. str1 corresponds to bit 0, str2 to bit 1, and so on. NULL values in str1, str2, ... are not appended to the result. mysql> SELECT MAKE_SET(1,'a','b','c'); -> 'a' mysql> SELECT MAKE_SET(1 | 4,'hello','nice','world'); -> 'hello,world' mysql> SELECT MAKE_SET(1 | 4,'hello','nice',NULL,'world'); -> 'hello' mysql> SELECT MAKE_SET(0,'a','b','c'); -> ''  
404 FIND_IN_SET 23 FIND_IN_SET(str,strlist) Returns a value 1 to N if the string str is in the string list strlist consisting of N substrings. A string list is a string composed of substrings separated by ',' characters. If the first argument is a constant string and the second is a column of type SET, the FIND_IN_SET() function is optimized to use bit arithmetic. Returns 0 if str is not in strlist or if strlist is the empty string. Returns NULL if either argument is NULL. This function does not work properly if the first argument contains a comma (',') character. mysql> SELECT FIND_IN_SET('b','a,b,c,d'); -> 2  

query result ( 405 records )

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처음으로 만들 Helloworld 는 함수였습니다.

함수와 프로시져를 서로 만드는 법이 틀리죠. 하지만 구조가 많이 비슷합니다.


Functions

함수는 항상 리턴 값이 존재합니다. 그리고 꼭 하나의 값만 리턴합니다.

MySQL에서 자주 사용하는 CONCAT 라는 함수를 보겠습니다.


mysql> select concat(emp_name,' ',dept_id) from emps;

+------------------------------+

| concat(emp_name,' ',dept_id) |

+------------------------------+

| Roger 1 |

| John 2 |

| Alan 1 |

+------------------------------+

3 rows in set (0.00 sec)



위와 같이 두개의 글자를 합해서 하나의 글자로 리턴하는 CONCAT 함수를 보았습니다.

MySQL에서 제공하는 스트링 함수이지만 이제부터는 개발자가 직접 함수를 만들어 사용할수 있습니다.


함수는 꼭 Select 명령을 통해서만 결과를 볼수 있습니다.


Procedures



프로시져는 함수보다 작은 기능을 가지고 있습니다.

함수와 거의 같지만 리턴 값만 없다고 보시면 됩니다.

간단한 함수를 하나 만들어보겠습니다.


--------------------------------


create procedure helloprocedure()

select 'Hello Procedure' ;


---------------------------------


위에 Procedure를 실행시킬때는 call 이라는 명령어를 통해 실행시킵니다.


mysql> call helloprocedure();

+-----------------+

| Hello Procedure |

+-----------------+

| Hello Procedure |

+-----------------+

1 row in set (0.00 sec)


Query OK, 0 rows affected (0.00 sec)


이제 기존이 프로시져를 삭제하고 다시 생성해보겠습니다.

아래의 코드는 helloprocedure 라는 프로시져를 만들고

begin .. end 을 통해 작성하였습니다.

-------------------------------------------------

delimiter //


drop procedure if exists helloprocedure

//


create procedure helloprocedure()

begin

select 'Hello Procedure 2' ;

end

//

-------------------------------------------------


mysql> call helloprocedure() //

+-------------------+

| Hello Procedure 2 |

+-------------------+

| Hello Procedure 2 |

+-------------------+

1 row in set (0.00 sec)


Query OK, 0 rows affected (0.00 sec)


이제 여러분 간단하게 프로시져와 함수를 만들고 실행시키는 법에 대해서

간단하게 이해 하셨을거라 생각합니다.


http://mysql.gilfster.com/page.php?parent_id=1.1&page_id=1.1.4


SQLGate Development Team


http://www.antwiz.com


Blog : http://isql.blogspot.com/

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◈ 함수(Function)

 - 보통 값을 계산하고 결과값을 반환하기 위해서 함수를 많이 사용 합니다.

 - 대부분 구성이 프로시저와 유사 하지만 IN 파라미터만 사용 할 수 있습니다.

 - 반드시 반환될 값의 데이터 타입을 RETURN문에 선언해야 합니다.

 - 또한
PL/SQL블록 내에서 RETURN문을 통해서 반드시 값을 반환해야 합니다.
 


[Syntax]

CREATE OR REPLACE FUNCTION
function name
  [(argument...)]
  RETURN  datatype

    -- Datatype은 반환되는 값의 datatype입니다.

IS

   [변수 선언 부분]

BEGIN

  [PL/SQL Block]

    -- PL/SQL 블록에는 적어도 한 개의 RETURN 문이 있어야 합니다.
    -- PL/SQL Block은 함수가 수행할 내용을 정의한 몸체부분입니다.

END;

 



SQL> CREATE OR REPLACE FUNCTION FC_update_sal
         (v_empno         IN    NUMBER)

          -- 리턴되는 변수의 데이터타입을 꼭 정의해야 합니다
          RETURN NUMBER
 .

        IS


        v_sal  emp.sal%type;

        BEGIN


        UPDATE emp
        SET sal  = sal  * 1.1
        WHERE empno  = v_empno;
   
        COMMIT;
 
        SELECT sal
        INTO v_sal
        FROM emp
        WHERE empno = v_empno;

        -- 리턴문이 꼭 존재해야 합니다
        RETURN v_sal;


       END;

함수가 생성되었습니다.
 



설명..

이 함수에는 v_sal이라는 %type 변수가 사용되고 있습니다.
스칼라 데이터 타입을 참고하세요.
프로지저와 마찬가지로 세미콜론(;)으로 블록을 종료한 뒤 "/"를 붙여 코드를 끝마칩니다.



함수의 실행

먼저 함수의 반환값을 저장할 변수를 선언합니다.

SQL> VAR salary NUMBER;


EXECUTE 문을 이용해 함수를 실행합니다.
SQL>EXECUTE :salary := FC_update_sal(7900);

PL/SQL 처리가 정상적으로 완료되었습니다.


오라클 SQL에서 선언된 변수의 출력은 PRINT문을 사용합니다.
PRINT문으로 함수의 반환값을 저장한 salary의 값을 확인하면 됩니다.

SQL>PRINT salary;
 
    SALARY
----------
      1045

결과가 이렇게 나옵니다.

 

 

 ================================================
    * Oracle Community OracleClub.com
    * http://www.oracleclub.com
    * http://www.oramaster.net
    * 운영자 : 김정식 (oramaster _at_ empal.com)
  ================================================

 

<Function Sample>

 

CREATE OR REPLACE FUNCTION FC_SIDONG
   (v_sido_cd      IN VARCHAR2,
    v_sigungu_cd IN VARCHAR2,
    v_dongcd       IN VARCHAR2)

 

RETURN varchar2
IS
v_dongnm varchar2(60);

 

BEGIN

 

 SELECT  admin_dongnm
    INTO  v_dongnm
   FROM  dong_tb
 WHERE  sido_cd       = v_sido_cd
     AND  sigungu_cd  = v_sigungu_cd
     AND  dongcd        = v_dongcd ;

 

RETURN  v_dongnm;
END;

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PROCEDURE와 FUNCTION의 차이점



- 프로시저는 매개변수로 데이터를 전달받을 수도 있고, 빋지 않을 수도 있다.

  실행 후 프로시저는 호출한 프로그램에게 값을 반환할 수도 있고, 안 할 수도 있다.


- 함수도 매개변수로 데이터를 전달받을 수도 있고, 빋지 않을 수도 있다.

  그러나 함수는 프로시저와 다르게 실행 후 반드시 하나의 값을 반환(RETURN)한다.


- 생성방법과 호출방법이 다르다.



 

1. Stored PROCEDURE(프로시저)


 

- 생성방법



CREATE [OR REPLACE] PROCEDURE 프로시저명(매개변수1, ...) IS [지역변수선언; ]


BEGIN

   처리명령문;

   ......;


[EXCEPTION]

  [ 처리명령문;]

  [......;]


END [프로시저명];



- 호출방법 : SQL*PLUS 커맨드창에서 SQL>EXECUTE 프로시저명(매개변수1,...)




2. Function(함수)



- 생성방법



CREATE [OR REPLACE] Function 함수명(매개변수1, ...)

RETURN 데이터타입

IS [지역변수선언; ]


BEGIN

   처리명령문;

   ......;

   RETURN 변수명;


[EXCEPTION]

  [ 처리명령문;]

  [......;]


END [함수명];



- 호출방법 : SQL내장함수와 동일. SELECT문 내에서 사용하면 된다.

                 예를 들어, 함수명이 CONVERT라면,

                 SELECT CONVERT(매개변수1,...) FROM TABLE명

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