在不同的mysql版本中,很多特性和语法有可能是不一样的,我们怎么样才能知道当前版本的语法是什么样呢?最好的办法是学会使用mysql的帮助。方法很简单:
1.1 按照层次看帮助
如果不知道帮助能够提供些什么,可以一层一层往下看:
命令如下:
mysql>sss ? contentsnnn
You asked for helpabouthelpcategory:"Contents"
For more information, type 'help<item>', where <item>isone of thefollowing
categories:
AccountManagement
Administration
Data Definition
Data Manipulation
Data Types
Functions
FunctionsandModifiersfor Usewith GROUPBY
GeographicFeatures
LanguageStructure
Plugins
Storage Engines
Stored Routines
Table Maintenance
Transactions
Triggers
对于列出的分类,可以进行看自己感兴趣的部分,例如:
mysqsssl> ? datatatattyppppes
You asked for helpabouthelpcategory: "DataTypes"
For more information, type'help<item>', where <item> isone of thefollowing
topics:
AUTO_INCREMENT
BIGINT
BINARY
BIT
BLOB
BLOBDATA TYPE
BOOLEAN
。。。。。。
对于列出的具体数据类型,可以进一步看详细情况:
mysql>sss ? int
Name: 'INT'
Description:
INT[(M)] [UNSIGNED][ZEROFILL]
A normal-sizeinteger.The signedrangeis-2147483648 to 2147483647.
The unsignedrangeis0to 4294967295.
1.2 快速查阅帮助
实际当中,如果我们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,我想
知道show命令都能看些什么东西,可以用如下命令:
mysql>sss ? showwww
Name: 'SHOW'
Description:
SHOWhas many forms thatprovideinformation aboutdatabases, tables,
columns,or statusinformation aboutthe server.Thissectiondescribes
those following:
SHOWAUTHORS
SHOWCHARACTERSET[LIKE 'pattern']
SHOWCOLLATION[LIKE 'pattern']
SHOW[FULL]COLUMNSFROM tbl_name[FROM db_name] [LIKE 'pattern']
SHOWCONTRIBUTORS
SHOWCREATEDATABASEdb_name
SHOWCREATEEVENT event_name
SHOWCREATEFUNCTION funcname
。。。。。。
我想知道createtable的语法,可以命令如下:
mysql>sss ? createttt tablebbb
Name: 'CREATETABLE'
Description:
Syntax:
CREATE[TEMPORARY]TABLE[IFNOT EXISTS]tbl_name
(create_definition,...)
[table_option...]
[partition_options]
Or:
CREATE[TEMPORARY]TABLE[IFNOT EXISTS]tbl_name
[(create_definition,...)]
[table_option...]
[partition_options]
select_statement
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