获得MySQL帮助
获得帮助的途径
- 一、官方文档
- 二、mysql客户端工具
- 三、? show 命令（查看一些数据库创建的DDL，事件的DDL）
一、官方文档
http://dev.mysql.com/doc/refman/5.7/en/
二、mysql客户端工具
# mysql -uroot -p -S /data/mysql_3306/mysql.sock
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 12
Server version: 5.6.29-log Source distribution
mysql> help //输入hel 或者 ? 就显示客户端的帮助，而不是服务器端。
clear (\c) Clear the current input statement.
#清除当前的sql输入语句，如输错sql语句（未加分号时）回车，可跳出当前的输入。当然也可以在语句后输入分号结束，但有报错信息。
connect (\r) Reconnect to the server. Optional arguments are db and host.
#mysql的连接被服务器复位了，没必要exit重新连。通过 connect 数据库名 主机名 连接即可
delimiter (\d) Set statement delimiter.
#修改执行符号，通常是“分号”，写存储过程时有很多sql需要分号分隔开，但mysql检测到分号会执行该sql语句，存储过程就写不完了。所以delimiter就解决这个问题，改变当然执行的符号。
edit (\e) Edit command with $EDITOR.
#修改SQL语句，如写了很长（而且有换行）前面有错要修改，会自动调用VI。wq保存退出加 ; 回车就可以执行了
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 (\n) Disable pager, print to stdout.
notee (\t) Don't write into outfile.
pager (\P) Set PAGER [to_pager]. Print the query results via PAGER.
#查询很多数据的表，让我们控制翻屏显示。
如mysql> pager less；select * from information_schema.tables\G;
print (\p) Print current command.
prompt (\R) Change your mysql prompt.
#修改mysql的提示符 可以在my.cnf中的[mysql]章节中定义
quit (\q) Quit mysql.
rehash (\#) Rebuild completion hash.
source (\.) Execute an SQL script file. Takes a file name as an argument.
#从外部执行一个sql脚本
status (\s) Get status information from the server.
#获得mysql服务器的状态信息（当前连接id,用户、数据库、字符集、启动时间等）
system (\!) Execute a system shell command.
#后跟操作系统命令，显示系统操作的结果，这样就不用退出mysql再执行系统命令了。
tee (\T) Set outfile [to_outfile]. Append everything into given outfile.
#把查询结果输入到给定文件中去
use (\u) Use another database. Takes database name as argument.
#切换当前使用的数据库
charset (\C) Switch to another charset. Might be needed for processing binlog with multi-byte charsets.
#改变字符集 如：charset gbk (改变客户端和连接的字符集，可用status查看)
warnings (\W) Show warnings after every statement.
#在每一个语句后显示警告信息。
nowarning (\w) Don't show warnings after every statement.
#不显示警告信息
For server side help, type 'help contents'
#查看服务器端帮助，使用help contents
1、prompt示例
mysql> prompt #
PROMPT set to '#'
#select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
#
#prompt mysql>
PROMPT set to 'mysql>'
mysql>
mysql> prompt [\h:] \u@mysql \d \R:\m:\s >
PROMPT set to '[\h:] \u@mysql \d \R:\m:\s > '
[localhost:] root@mysql (none) 20:02:09 > use test
Database changed
[localhost:] root@mysql test 20:02:15 > show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
2、delimiter示例
mysql> delimiter $$
mysql> show databases;
-> $$
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
3、status示例
mysql> status
--------------
mysql Ver 14.14 Distrib 5.6.29, for Linux (x86_64) using EditLine wrapper
Connection id: 20
Current database:
Current user: root@localhost
SSL: Not in use
Current pager: stdout
Using outfile: ''
Using delimiter: ;
Server version: 5.6.29-log Source distribution
Protocol version: 10
Connection: Localhost via UNIX socket
Server characterset: latin1
Db characterset: latin1
Client characterset: utf8
Conn. characterset: utf8
UNIX socket: /data/mysql_3306/mysql.sock
Uptime: 1 hour 29 min 15 sec
Threads: 1 Questions: 117 Slow queries: 5 Opens: 87 Flush tables: 1 Open tables: 80 Queries per second avg: 0.021
--------------
mysql>
4、tee示例
mysql> \! > /tmp/tee.txt
mysql> tee /tmp/tee.txt
Logging to file '/tmp/tee.txt'
mysql> use test;
Database changed
mysql> select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
mysql> \! cat /tmp/tee.txt
mysql> \! > /tmp/tee.txt
mysql> tee /tmp/tee.txt
mysql> use test;
Database changed
mysql> select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
5、查看服务器端帮助
mysql> 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
Storage Engines
Table Maintenance
Transactions
User-Defined Functions
Utility
mysql> help administration
You asked for help about help category: "Administration"
For more information, type 'help <item>', where <item> is one of the following
topics:
BINLOG
CACHE INDEX
FLUSH
FLUSH QUERY CACHE
HELP COMMAND
KILL
LOAD INDEX
RESET
SET
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
```
## 三、show 命令
? show 命令（查看一些数据库创建的DDL，事件的DDL）
```mysql
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/5.6/en/extended-show.html.
URL: http://dev.mysql.com/doc/refman/5.6/en/show.html
mysql> ? show create database
Name: 'SHOW CREATE DATABASE'
Description:
Syntax:
SHOW CREATE {DATABASE | SCHEMA} [IF NOT EXISTS] db_name
Shows the CREATE DATABASE statement that creates the named database. If
the SHOW statement includes an IF NOT EXISTS clause, the output too
includes such a clause. SHOW CREATE SCHEMA is a synonym for SHOW CREATE
DATABASE.
URL: http://dev.mysql.com/doc/refman/5.6/en/show-create-database.html
Examples:
mysql> SHOW CREATE DATABASE test\G
*************************** 1. row ***************************
Database: test
Create Database: CREATE DATABASE `test`
/*!40100 DEFAULT CHARACTER SET latin1 */
mysql> SHOW CREATE SCHEMA test\G
*************************** 1. row ***************************
Database: test
Create Database: CREATE DATABASE `test`
/*!40100 DEFAULT CHARACTER SET latin1 */
? show;
help contents;
help data definition;
help create database;
SHOW CHARACTER SET;
show collation;