mysql基础之帮助信息

在mysql中获取帮助

1、当连接到mysql数据库以后，使用help命令或者?表示获取帮助信息：

MariaDB [ren]> help

General information about MariaDB can be found at
http://mariadb.org

List of all MySQL commands:
Note that all text commands must be first on line and end with ';'
?         (?) Synonym for `help'.
clear     (c) Clear the current input statement.
connect   (
) Reconnect to the server. Optional arguments are db and host.
delimiter (d) Set statement delimiter.
edit      (e) Edit command with $EDITOR.
ego       (G) Send command to mysql server, display result vertically.
exit      (q) Exit mysql. Same as quit.
go        (g) Send command to mysql server.
help      (h) Display this help.
nopager   (
) Disable pager, print to stdout.
notee     (	) Don't write into outfile.
pager     (P) Set PAGER [to_pager]. Print the query results via PAGER.
print     (p) Print current command.
prompt    (R) Change your mysql prompt.
quit      (q) Quit mysql.
rehash    (#) Rebuild completion hash.
source    (.) Execute an SQL script file. Takes a file name as an argument.
status    (s) Get status information from the server.
system    (!) Execute a system shell command.
tee       (T) Set outfile [to_outfile]. Append everything into given outfile.
use       (u) Use another database. Takes database name as argument.
charset   (C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets.
warnings  (W) Show warnings after every statement.
nowarning (w) Don't show warnings after every statement.

For server side help, type 'help contents'

2、指定关键字查看具体命令对应的帮助信息：

MariaDB [ren]> help create
Many help items for your request exist.
To make a more specific request, please type 'help <item>',
where <item> is one of the following
topics:
   CREATE DATABASE
   CREATE EVENT
   CREATE FUNCTION
   CREATE FUNCTION UDF
   CREATE INDEX
   CREATE PROCEDURE
   CREATE SERVER
   CREATE TABLE
   CREATE TABLESPACE
   CREATE TRIGGER
   CREATE USER
   CREATE VIEW
   SHOW
   SHOW CREATE DATABASE
   SHOW CREATE EVENT
   SHOW CREATE FUNCTION
   SHOW CREATE PROCEDURE
   SHOW CREATE TABLE
   SPATIAL

3、上面列出了与“create”关键字相关的命令，同样，把列出的命令再次使用help查看即可获得对应命令的语法：

MariaDB [ren]> help create database
Name: 'CREATE DATABASE'
Description:
Syntax:
CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
    [create_specification] ...

create_specification:
    [DEFAULT] CHARACTER SET [=] charset_name
  | [DEFAULT] COLLATE [=] collation_name

CREATE DATABASE creates a database with the given name. To use this
statement, you need the CREATE privilege for the database. CREATE
SCHEMA is a synonym for CREATE DATABASE.

URL: https://mariadb.com/kb/en/create-database/

4、可以通过help contents命令查看mysql将帮助分为了哪几类：

MariaDB [ren]> help 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
   Table Maintenance
   Transactions
   User-Defined Functions
   Utility

5、查看数据类型的帮助信息：

MariaDB [ren]> help '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