MySQL帮助的使用

要想早日成为数据库的大牛，学会使用帮助文档很重要，当碰到问题的时候，可以快速拿出葵花宝典这个利器解决问题，哈哈。

文档的获取，网上百度，这个可以说最方便，但是作为一个运维人员的话，有可能你远程的机器不能使用外网。

命令行帮助
？ contents 显示所有可供查询的分类

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

mysql>

敲入对应的分类即可查看具体信息，举例

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

一步一步根据提示，可以知道INT数据类型的范围大小区间

mysql> help 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/5.6/en/numeric-type-overview.html

除此之外，还可以敲入关键字获取帮助文档，如? insert,? create table

mysql> ? insert
Name: 'INSERT'
Description:
Syntax:
INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [PARTITION (partition_name,...)]
    [(col_name,...)]
    {VALUES | VALUE} ({expr | DEFAULT},...),(...),...
    [ ON DUPLICATE KEY UPDATE
      col_name=expr
        [, col_name=expr] ... ]

Or:

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [PARTITION (partition_name,...)]
    SET col_name={expr | DEFAULT}, ...
    [ ON DUPLICATE KEY UPDATE
      col_name=expr
        [, col_name=expr] ... ]

Or:

INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [PARTITION (partition_name,...)]
    [(col_name,...)]
    SELECT ...
    [ ON DUPLICATE KEY UPDATE
      col_name=expr
        [, col_name=expr] ... ]

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. INSERT ... SELECT is discussed
further in [HELP INSERT SELECT].

In MySQL 5.6.2 and later, when inserting into a partitioned table, you
can control which partitions and subpartitions accept new rows. The
PARTITION option takes a comma-separated list of the names of one or
more partitions or subpartitions (or both) of the table. If any of the
rows to be inserted by a given INSERT statement do not match one of the
partitions listed, the INSERT statement fails with the error Found a
row not matching the given partition set. See
http://dev.mysql.com/doc/refman/5.6/en/partitioning-selection.html, for
more information and examples.

URL: http://dev.mysql.com/doc/refman/5.6/en/insert.html

如果没有命令行帮助新，可以导入mysql目录下的share文件夹下的fill_help_tables.sql

MySQL帮助的使用

感叹：大公司开发的东西，文档各方面都为我们考虑到了，看齐，要看齐