高效查看MySQL帮助文档的方法

在mysql的使用过程中, 可能经常会遇到以下问题:

• 某个操作语法忘记了, 如何快速查找?
• 如何快速知道当前版本上某个字段类型的取值范围?
• 当前版本都支持哪些函数?希望有例子说明..
• 当前版本是否支持某个功能?

    对于上面列出的问题, 我们可能想到的方法是查找MySQL的文档, 这些问题在官方文档都可以很清楚地查到, 但是却要耗费大量的时间和精力.

    所以对于以上问题, 最好的解决办法就是使用MySQL安装后自带的帮助文档, 这样在遇到问题时就可以方便快捷地进行查询.

 

 

按层次查看帮助

查看目录    

如果不知道帮助能够提供些什么, 可以用"? contents"命令来显示所有可供查询的分类, 如下例所示:

mysql> ? contents
You asked for help about help category: "Contents"
For more information, type 'help <item>', where <item> is one of the following
categories:
   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
   Procedures
   Storage Engines
   Table Maintenance
   Transactions
   User-Defined Functions
   Utility

查看数据类型

对于列出的分类, 可以使用"? 类别名称"的方式针对用户感兴趣的内容做进一步的查看, 例如, 想看看MySQL都支持哪些数据类型, 可以执行"? data tyeps"命令:

mysql> ? data types
You asked for help about help category: "Data Types"
For more information, type 'help <item>', where <item> is one of the following
topics:
   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 TYPE

上面列出了此版本支持的所有数据类型, 如果想知道int类型的具体介绍, 也可以利用上面的方法, 做进一步的查看:

mysql> ? int
Name: 'INT'
Description:
INT[(M)] [UNSIGNED] [ZEROFILL]
A normal-size integer. The signed range is -2147483648 to 2147483647.
The unsigned range is 0 to 4294967295.
URL: http://dev.mysql.com/doc/refman/5.5/en/numeric-type-overview.html

查看函数

mysql> ? functions
You asked for help about help category: "Functions"
For more information, type 'help <item>', where <item> is one of the following
categories:
   Bit Functions
   Comparison operators
   Control flow functions
   Date and Time Functions
   Encryption Functions
   Information Functions
   Logical operators
   Miscellaneous Functions
   Numeric Functions
   String Functions

再根据列出的目录查看相应函数,比如查看都有什么日期函数

mysql> ? Date and Time Functions
You asked for help about help category: "Date and Time Functions"
For more information, type 'help <item>', where <item> is one of the following
topics:
   ADDDATE
   ADDTIME
   CONVERT_TZ
   CURDATE
   CURRENT_DATE
   CURRENT_TIME
   CURRENT_TIMESTAMP
   CURTIME
   DATE FUNCTION
   DATEDIFF
   DATE_ADD
   DATE_FORMAT
   DATE_SUB
   DAY
   DAYNAME
   DAYOFMONTH
   DAYOFWEEK
   DAYOFYEAR
   EXTRACT
   FROM_DAYS
   FROM_UNIXTIME
   GET_FORMAT
   HOUR
   LAST_DAY
   LOCALTIME
   LOCALTIMESTAMP
   MAKEDATE
   MAKETIME
   MICROSECOND
   MINUTE
   MONTH
   MONTHNAME
   NOW
   PERIOD_ADD
   PERIOD_DIFF
   QUARTER
   SECOND
   SEC_TO_TIME
   STR_TO_DATE
   SUBDATE
   SUBTIME
   SYSDATE
   TIME FUNCTION
   TIMEDIFF
   TIMESTAMP FUNCTION
   TIMESTAMPADD
   TIMESTAMPDIFF
   TIME_FORMAT
   TIME_TO_SEC
   TO_DAYS
   TO_SECONDS
   UNIX_TIMESTAMP
   UTC_DATE
   UTC_TIME
   UTC_TIMESTAMP
   WEEK
   WEEKDAY
   WEEKOFYEAR
   YEAR
   YEARWEEK

 

快速查阅帮助

    在实际应用当中, 如果需要快速查阅某项语法时, 可以使用关键字进行快速查询. 例如, 想知道show命令都能看到什么东西, 可以用如下命令:

mysql> ? show
Name: 'SHOW'
Description:
SHOW has many forms that provide information about databases, tables,
columns, or status information about the server. This section describes
those following:
SHOW AUTHORS
SHOW {BINARY | MASTER} LOGS
SHOW BINLOG EVENTS [IN 'log_name'] [FROM pos] [LIMIT [offset,] row_count]
SHOW CHARACTER SET [like_or_where]
SHOW COLLATION [like_or_where]
SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [like_or_where]
SHOW CONTRIBUTORS
SHOW CREATE DATABASE db_name
SHOW CREATE EVENT event_name
SHOW CREATE FUNCTION func_name
SHOW CREATE PROCEDURE proc_name
SHOW CREATE TABLE tbl_name
SHOW CREATE TRIGGER trigger_name
SHOW CREATE VIEW view_name
SHOW DATABASES [like_or_where]
SHOW ENGINE engine_name {STATUS | MUTEX}
SHOW [STORAGE] ENGINES
SHOW ERRORS [LIMIT [offset,] row_count]
SHOW EVENTS
SHOW FUNCTION CODE func_name
SHOW FUNCTION STATUS [like_or_where]
SHOW GRANTS FOR user
SHOW INDEX FROM tbl_name [FROM db_name]
SHOW MASTER STATUS
SHOW OPEN TABLES [FROM db_name] [like_or_where]
SHOW PLUGINS
SHOW PROCEDURE CODE proc_name
SHOW PROCEDURE STATUS [like_or_where]
SHOW PRIVILEGES
SHOW [FULL] PROCESSLIST
SHOW PROFILE [types] [FOR QUERY n] [OFFSET n] [LIMIT n]
SHOW PROFILES
SHOW SLAVE HOSTS
SHOW SLAVE STATUS
SHOW [GLOBAL | SESSION] STATUS [like_or_where]
SHOW TABLE STATUS [FROM db_name] [like_or_where]
SHOW [FULL] TABLES [FROM db_name] [like_or_where]
SHOW TRIGGERS [FROM db_name] [like_or_where]
SHOW [GLOBAL | SESSION] VARIABLES [like_or_where]
SHOW WARNINGS [LIMIT [offset,] row_count]
like_or_where:
    LIKE 'pattern'
  | WHERE expr
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.
Several SHOW statements also accept a WHERE clause that provides more
flexibility in specifying which rows to display. See
http://dev.mysql.com/doc/refman/5.5/en/extended-show.html.
URL: http://dev.mysql.com/doc/refman/5.5/en/show.html

例如, 想查看某个函数CONCAT的使用

mysql> ? concat
Name: 'CONCAT'
Description:
Syntax:
CONCAT(str1,str2,...)
Returns the string that results from concatenating the arguments. May
have one or more arguments. If all arguments are nonbinary strings, the
result is a nonbinary string. If the arguments include any binary
strings, the result is a binary string. A numeric argument is converted
to its equivalent string form. This is a nonbinary string as of MySQL
5.5.3. Before 5.5.3, it is a binary string; to to avoid that and
produce a nonbinary string, you can use an explicit type cast, as in
this example:
SELECT CONCAT(CAST(int_col AS CHAR), char_col);
CONCAT() returns NULL if any argument is NULL.
URL: http://dev.mysql.com/doc/refman/5.5/en/string-functions.html
Examples:
mysql> SELECT CONCAT('My', 'S', 'QL');
        -> 'MySQL'
mysql> SELECT CONCAT('My', NULL, 'QL');
        -> NULL
mysql> SELECT CONCAT(14.3);
        -> '14.3'

又例如, 如果想查看create table的语法, 可以使用以下命令:

mysql> ? 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_statement
Or:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
    { LIKE old_tbl_name | (LIKE old_tbl_name) }
    ......

再举一个例子吧, 比如想查看创建用户GRANT语法怎么写

mysql> ? grant
Name: 'GRANT'
Description:
Syntax:
GRANT
    priv_type [(column_list)]
      [, priv_type [(column_list)]] ...
    ON [object_type] priv_level
    TO user_specification [, user_specification] ...
    [REQUIRE {NONE | ssl_option [[AND] ssl_option] ...}]
    [WITH with_option ...]
GRANT PROXY ON user_specification
    TO user_specification [, user_specification] ...
    [WITH GRANT OPTION]
object_type:
    TABLE
  | FUNCTION
  | PROCEDURE
      ......

下面把查看手册和官方资料的地址献上, 就把衣钵都传给你们了, 别忘了给个赞哦~

 

常用的网络资源

http://dev.mysql.com/downloads/是MySQL的官方网站, 可以下载到各个版本的MySQL以及相关客户端开发工具等.

http://dev.mysql.com/doc/提供了目前最权威的MySQL数据库及工具的在线手册

http://bugs.mysql.com/ 这里可以查看到MySQL已经发布的bug列表, 或者向MySQL提交bug报告

http://www.mysql.com/news-and-events/newsletter/通常会发布各种关于MySQL的最新消息.