mysql 帮助文档使用

mysql有很完善的帮助文档，在mysql命令行下可以通过？ 或者help 加上命令可以查看改命令的帮助信息，

我们查下几个常用的help命令

 

第一层帮助信息：

 ？ contents;

mysql> ? contents;You asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of the followingcategories:   Account Management   Administration   Compound Statements   Data Definition   Data Manipulation   Data Types   Functions   Functions and Modifiers for Use with GROUP BY   Geographic Features   Help Metadata   Language Structure   Plugins   Table Maintenance   Transactions   User-Defined Functions   Utility

再查看具体每一层的帮助信息

 

  mysql> ? Account Management;

You asked for help about help category: "Account Management"For more information, type 'help <item>', where <item> is one of the followingtopics:   CREATE USER   DROP USER   GRANT   RENAME USER   REVOKE   SET PASSWORDmysql> ? AdministrationYou asked for help about help category: "Administration"For more information, type 'help <item>', where <item> is one of the followingtopics:   BINLOG   CACHE INDEX   CHANGE MASTER TO   DEALLOCATE PREPARE   EXECUTE STATEMENT   FLUSH   FLUSH QUERY CACHE   HELP COMMAND   KILL   LOAD INDEX   PREPARE   PURGE BINARY LOGS   RESET   RESET MASTER   RESET SLAVE   SET   SET GLOBAL SQL_SLAVE_SKIP_COUNTER   SET SQL_LOG_BIN   SHOW   SHOW AUTHORS   SHOW BINARY LOGS   SHOW BINLOG EVENTS   SHOW CHARACTER SET   SHOW COLLATION   SHOW COLUMNS   SHOW CONTRIBUTORS   SHOW CREATE DATABASE   SHOW CREATE EVENT   SHOW CREATE FUNCTION   SHOW CREATE PROCEDURE   SHOW CREATE TABLE   SHOW CREATE TRIGGER   SHOW CREATE VIEW   SHOW DATABASES   SHOW ENGINE   SHOW ENGINES   SHOW ERRORS   SHOW EVENTS   SHOW FUNCTION CODE   SHOW FUNCTION STATUS   SHOW GRANTS   SHOW INDEX   SHOW MASTER STATUS   SHOW OPEN TABLES   SHOW PLUGINS   SHOW PRIVILEGES   SHOW PROCEDURE CODE   SHOW PROCEDURE STATUS   SHOW PROCESSLIST   SHOW PROFILE   SHOW PROFILES   SHOW RELAYLOG EVENTS   SHOW SLAVE HOSTS   SHOW SLAVE STATUS   SHOW STATUS   SHOW TABLE STATUS   SHOW TABLES   SHOW TRIGGERS   SHOW VARIABLES   SHOW WARNINGS   START SLAVE   STOP SLAVEmysql> ?  Compound Statements;You asked for help about help category: "Compound Statements"For more information, type 'help <item>', where <item> is one of the followingtopics:   BEGIN END   CASE STATEMENT   CLOSE   DECLARE CONDITION   DECLARE CURSOR   DECLARE HANDLER   DECLARE VARIABLE   FETCH   IF STATEMENT   ITERATE   LEAVE   LOOP   OPEN   REPEAT LOOP   RESIGNAL   RETURN   SELECT INTO   SET VARIABLE   SIGNAL   WHILEmysql> ? Data Definition;You asked for help about help category: "Data Definition"For more information, type 'help <item>', where <item> is one of the followingtopics:   ALTER DATABASE   ALTER EVENT   ALTER FUNCTION   ALTER PROCEDURE   ALTER SERVER   ALTER TABLE   ALTER VIEW   CONSTRAINT   CREATE DATABASE   CREATE EVENT   CREATE FUNCTION   CREATE INDEX   CREATE PROCEDURE   CREATE SERVER   CREATE TABLE   CREATE TRIGGER   CREATE VIEW   DROP DATABASE   DROP EVENT   DROP FUNCTION   DROP INDEX   DROP PROCEDURE   DROP SERVER   DROP TABLE   DROP TRIGGER   DROP VIEW   MERGE   RENAME TABLE   TRUNCATE TABLE

这里可以根据不同的分类显示每个分类下支持的mysql指令

 

  mysql> ? START SLAVE;

Name: 'START SLAVE'Description:Syntax:START SLAVE [thread_type [, thread_type] ... ]START SLAVE [SQL_THREAD] UNTIL    MASTER_LOG_FILE = 'log_name', MASTER_LOG_POS = log_posSTART SLAVE [SQL_THREAD] UNTIL    RELAY_LOG_FILE = 'log_name', RELAY_LOG_POS = log_posthread_type: IO_THREAD | SQL_THREADSTART SLAVE with no thread_type options starts both of the slavethreads. The I/O thread reads events from the master server and storesthem in the relay log. The SQL thread reads events from the relay logand executes them. START SLAVE requires the SUPER privilege.If START SLAVE succeeds in starting the slave threads, it returnswithout any error. However, even in that case, it might be that theslave threads start and then later stop (for example, because they donot manage to connect to the master or read its binary log, or someother problem). START SLAVE does not warn you about this. You mustcheck the slave's error log for error messages generated by the slavethreads, or check that they are running satisfactorily with SHOW SLAVESTATUS.URL: http://dev.mysql.com/doc/refman/5.5/en/start-slave.htmlmysql> ? MERGEName: 'MERGE'Description:The MERGE storage engine, also known as the MRG_MyISAM engine, is acollection of identical MyISAM tables that can be used as one."Identical" means that all tables have identical column and indexinformation. You cannot merge MyISAM tables in which the columns arelisted in a different order, do not have exactly the same columns, orhave the indexes in different order. However, any or all of the MyISAMtables can be compressed with myisampack. Seehttp://dev.mysql.com/doc/refman/5.5/en/myisampack.html. Differences intable options such as AVG_ROW_LENGTH, MAX_ROWS, or PACK_KEYS do notmatter.URL: http://dev.mysql.com/doc/refman/5.5/en/merge-storage-engine.htmlExamples:mysql> CREATE TABLE t1 (    ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,    ->    message CHAR(20)) ENGINE=MyISAMmysql> CREATE TABLE t2 (    ->    a INT NOT NULL AUTO_INCREMENT PRIMARY KEY,    ->    message CHAR(20)) ENGINE=MyISAMmysql> 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))    ->    ENGINE=MERGE UNION=(t1,t2) INSERT_METHOD=LASTmysql> ? create table;Name: 'CREATE TABLE'Description:Syntax:CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name    (create_definition,...)    [table_options]    [partition_options]Or:CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name    [(create_definition,...)]    [table_options]    [partition_options]    select_statementOr:CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name    { LIKE old_tbl_name | (LIKE old_tbl_name) }create_definition:    col_name column_definition  | [CONSTRAINT [symbol]] PRIMARY KEY [index_type] (index_col_name,...)      [index_option] ...  | {INDEX|KEY} [index_name] [index_type] (index_col_name,...)      [index_option] ...  | [CONSTRAINT [symbol]] UNIQUE [INDEX|KEY]      [index_name] [index_type] (index_col_name,...)      [index_option] ...  | {FULLTEXT|SPATIAL} [INDEX|KEY] [index_name] (index_col_name,...)      [index_option] ...  | [CONSTRAINT [symbol]] FOREIGN KEY      [index_name] (index_col_name,...) reference_definition  | CHECK (expr)column_definition:    data_type [NOT NULL | NULL] [DEFAULT default_value]      [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]      [COMMENT 'string']      [COLUMN_FORMAT {FIXED|DYNAMIC|DEFAULT}]      [reference_definition]data_type:    BIT[(length)]  | TINYINT[(length)] [UNSIGNED] [ZEROFILL]  | SMALLINT[(length)] [UNSIGNED] [ZEROFILL]  | MEDIUMINT[(length)] [UNSIGNED] [ZEROFILL]  | INT[(length)] [UNSIGNED] [ZEROFILL]  | INTEGER[(length)] [UNSIGNED] [ZEROFILL]  | BIGINT[(length)] [UNSIGNED] [ZEROFILL]  | REAL[(length,decimals)] [UNSIGNED] [ZEROFILL]  | DOUBLE[(length,decimals)] [UNSIGNED] [ZEROFILL]  | FLOAT[(length,decimals)] [UNSIGNED] [ZEROFILL]  | DECIMAL[(length[,decimals])] [UNSIGNED] [ZEROFILL]  | NUMERIC[(length[,decimals])] [UNSIGNED] [ZEROFILL]  | DATE  | TIME  | TIMESTAMP  | DATETIME  | YEAR  | CHAR[(length)]      [CHARACTER SET charset_name] [COLLATE collation_name]  | VARCHAR(length)      [CHARACTER SET charset_name] [COLLATE collation_name]  | BINARY[(length)]  | VARBINARY(length)  | TINYBLOB  | BLOB  | MEDIUMBLOB  | LONGBLOB  | TINYTEXT [BINARY]      [CHARACTER SET charset_name] [COLLATE collation_name]  | TEXT [BINARY]      [CHARACTER SET charset_name] [COLLATE collation_name]  | MEDIUMTEXT [BINARY]      [CHARACTER SET charset_name] [COLLATE collation_name]  | LONGTEXT [BINARY]      [CHARACTER SET charset_name] [COLLATE collation_name]  | ENUM(value1,value2,value3,...)      [CHARACTER SET charset_name] [COLLATE collation_name]  | SET(value1,value2,value3,...)      [CHARACTER SET charset_name] [COLLATE collation_name]  | spatial_typeindex_col_name:    col_name [(length)] [ASC | DESC]index_type:    USING {BTREE | HASH}index_option:    KEY_BLOCK_SIZE [=] value  | index_type  | WITH PARSER parser_name  | COMMENT 'string'reference_definition:    REFERENCES tbl_name (index_col_name,...)      [MATCH FULL | MATCH PARTIAL | MATCH SIMPLE]      [ON DELETE reference_option]      [ON UPDATE reference_option]reference_option:    RESTRICT | CASCADE | SET NULL | NO ACTIONtable_options:    table_option [[,] table_option] ...table_option:    ENGINE [=] engine_name  | AUTO_INCREMENT [=] value  | AVG_ROW_LENGTH [=] value  | [DEFAULT] CHARACTER SET [=] charset_name  | CHECKSUM [=] {0 | 1}  | [DEFAULT] COLLATE [=] collation_name  | COMMENT [=] 'string'  | CONNECTION [=] 'connect_string'  | DATA DIRECTORY [=] 'absolute path to directory'  | DELAY_KEY_WRITE [=] {0 | 1}  | INDEX DIRECTORY [=] 'absolute path to directory'  | INSERT_METHOD [=] { NO | FIRST | LAST }  | KEY_BLOCK_SIZE [=] value  | MAX_ROWS [=] value  | MIN_ROWS [=] value  | PACK_KEYS [=] {0 | 1 | DEFAULT}  | PASSWORD [=] 'string'  | ROW_FORMAT [=] {DEFAULT|DYNAMIC|FIXED|COMPRESSED|REDUNDANT|COMPACT}  | UNION [=] (tbl_name[,tbl_name]...)partition_options:    PARTITION BY        { [LINEAR] HASH(expr)        | [LINEAR] KEY(column_list)        | RANGE{(expr) | COLUMNS(column_list)}        | LIST{(expr) | COLUMNS(column_list)} }    [PARTITIONS num]    [SUBPARTITION BY        { [LINEAR] HASH(expr)        | [LINEAR] KEY(column_list) }      [SUBPARTITIONS num]    ]    [(partition_definition [, partition_definition] ...)]partition_definition:    PARTITION partition_name        [VALUES            {LESS THAN {(expr | value_list) | MAXVALUE}            |            IN (value_list)}]        [[STORAGE] ENGINE [=] engine_name]        [COMMENT [=] 'comment_text' ]        [DATA DIRECTORY [=] 'data_dir']        [INDEX DIRECTORY [=] 'index_dir']        [MAX_ROWS [=] max_number_of_rows]        [MIN_ROWS [=] min_number_of_rows]        [(subpartition_definition [, subpartition_definition] ...)]subpartition_definition:    SUBPARTITION logical_name        [[STORAGE] ENGINE [=] engine_name]        [COMMENT [=] 'comment_text' ]        [DATA DIRECTORY [=] 'data_dir']        [INDEX DIRECTORY [=] 'index_dir']        [MAX_ROWS [=] max_number_of_rows]        [MIN_ROWS [=] min_number_of_rows]select_statement:    [IGNORE | REPLACE] [AS] SELECT ...   (Some legal select statement)CREATE TABLE creates a table with the given name. You must have theCREATE privilege for the table.Rules for permissible table names are given inhttp://dev.mysql.com/doc/refman/5.5/en/identifiers.html. By default,the table is created in the default database, using the InnoDB storageengine. An error occurs if the table exists, if there is no defaultdatabase, or if the database does not exist.URL: http://dev.mysql.com/doc/refman/5.5/en/create-table.htmlmysql>

至于上面一层的命令，我们还可以查看mysql支持的数据类型，

mysql> ? Data Types;You asked for help about help category: "Data Types"For more information, type 'help <item>', where <item> is one of the followingtopics:   AUTO_INCREMENT   BIGINT   BINARY   BIT   BLOB   BLOB DATA TYPE   BOOLEAN   CHAR   CHAR BYTE   DATE   DATETIME   DEC   DECIMAL   DOUBLE   DOUBLE PRECISION   ENUM   FLOAT   INT   INTEGER   LONGBLOB   LONGTEXT   MEDIUMBLOB   MEDIUMINT   MEDIUMTEXT   SET DATA TYPE   SMALLINT   TEXT   TIME   TIMESTAMP   TINYBLOB   TINYINT   TINYTEXT   VARBINARY   VARCHAR   YEAR DATA TYPEmysql> ? Utility;You asked for help about help category: "Utility"For more information, type 'help <item>', where <item> is one of the followingtopics:   DESCRIBE   EXPLAIN   HELP STATEMENT   USE

通过帮助文档还是很方便查到mysql的所有名称，已经每个命令的使用方法和语法。

 

可以查看mysql内置函数列表，以及每个函数的功能和使用方法：

mysql> ? Functions;You asked for help about help category: "Functions"For more information, type 'help <item>', where <item> is one of the followingtopics:   PROCEDURE ANALYSEcategories:   Bit Functions   Comparison operators   Control flow functions   Date and Time Functions   Encryption Functions   Information Functions   Logical operators   Miscellaneous Functions   Numeric Functions   String Functionsmysql> ? String Functions;You asked for help about help category: "String Functions"For more information, type 'help <item>', where <item> is one of the followingtopics:   ASCII   BIN   BINARY OPERATOR   BIT_LENGTH   CAST   CHAR FUNCTION   CHARACTER_LENGTH   CHAR_LENGTH   CONCAT   CONCAT_WS   CONVERT   ELT   EXPORT_SET   EXTRACTVALUE   FIELD   FIND_IN_SET   FORMAT   HEX   INSERT FUNCTION   INSTR   LCASE   LEFT   LENGTH   LIKE   LOAD_FILE   LOCATE   LOWER   LPAD   LTRIM   MAKE_SET   MATCH AGAINST   MID   NOT LIKE   NOT REGEXP   OCTET_LENGTH   ORD   POSITION   QUOTE   REGEXP   REPEAT FUNCTION   REPLACE FUNCTION   REVERSE   RIGHT   RPAD   RTRIM   SOUNDEX   SOUNDS LIKE   SPACE   STRCMP   SUBSTR   SUBSTRING   SUBSTRING_INDEX   TRIM   UCASE   UNHEX   UPDATEXML   UPPERmysql> ? QUOTE;Name: 'QUOTE'Description:Syntax:QUOTE(str)Quotes a string to produce a result that can be used as a properlyescaped data value in an SQL statement. The string is returned enclosedby single quotation marks and with each instance of backslash ("\"),single quote ("'"), ASCII NUL, and Control+Z preceded by a backslash.If the argument is NULL, the return value is the word "NULL" withoutenclosing single quotation marks.URL: http://dev.mysql.com/doc/refman/5.5/en/string-functions.htmlExamples:mysql> SELECT QUOTE('Don\'t!')        -> 'Don\'t!'mysql> SELECT QUOTE(NULL)        -> NULLmysql>

mysql的插件信息和事务之类的其他信息

mysql> ? Plugins;Name: 'SHOW PLUGINS'Description:Syntax:SHOW PLUGINSSHOW PLUGINS displays information about server plugins. Plugininformation is also available in the INFORMATION_SCHEMA.PLUGINS table.See http://dev.mysql.com/doc/refman/5.5/en/plugins-table.html.Example of SHOW PLUGINS output:mysql> SHOW PLUGINS\G*************************** 1. row ***************************   Name: binlog Status: ACTIVE   Type: STORAGE ENGINELibrary: NULLLicense: GPL*************************** 2. row ***************************   Name: CSV Status: ACTIVE   Type: STORAGE ENGINELibrary: NULLLicense: GPL*************************** 3. row ***************************   Name: MEMORY Status: ACTIVE   Type: STORAGE ENGINELibrary: NULLLicense: GPL*************************** 4. row ***************************   Name: MyISAM Status: ACTIVE   Type: STORAGE ENGINELibrary: NULLLicense: GPL...URL: http://dev.mysql.com/doc/refman/5.5/en/show-plugins.htmlmysql> ? Transations;Nothing foundPlease try to run 'help contents' for a list of all accessible topicsmysql> ? Transactions;You asked for help about help category: "Transactions"For more information, type 'help <item>', where <item> is one of the followingtopics:   ISOLATION   LOCK   SAVEPOINT   START TRANSACTIONmysql>

通过帮助文档可以查询到mysql的所有命令及每个命令的功能，语法。