MySQL的show命令语法
SHOW命令有许多种格式，用来查看数据库，表，列和服务器状态信息。 SHOW命令后面可以带 LIKE 用于匹配，有的SHOW后面还可以跟WHERE条件。
show命令的官方手册： http://dev.mysql.com/doc/refman/5.7/en/show.html
命令集合
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 {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 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 [NONBLOCKING]
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/5.7/en/extended-show.html.
URL: http://dev.mysql.com/doc/refman/5.7/en/show.html
归纳
表相关的：
SHOW INDEX FROM tbl_name [FROM db_name]
SHOW [FULL] COLUMNS FROM tbl_name [FROM db_name] [like_or_where]
SHOW TABLE STATUS [FROM db_name] [like_or_where]
查看用户的权限：
SHOW GRANTS FOR root;
查看表的列信息：
SHOW COLUMNS FROM user;
查看表的索引：
SHOW INDEX FROM user;
查看表的状态：
mysql> SHOW TABLE STATUS FROM mysql WHERE Name='user'\G;
*************************** 1. row ***************************
Name: user
Engine: MyISAM
Version: 10
Row_format: Dynamic
Rows: 3
Avg_row_length: 122
Data_length: 368
Max_data_length: 281474976710655
Index_length: 4096
Data_free: 0
Auto_increment: NULL
Create_time: 2015-12-23 19:28:52
Update_time: 2016-01-28 10:56:07
Check_time: NULL
Collation: utf8_bin
Checksum: NULL
Create_options:
Comment: Users and global privileges
1 row in set (0.00 sec)
查看系统支持的字符集：
SHOW CHARACTER SET
查看系统支持的权限：
SHOW PRIVILEGES;
查看系统所有的引擎：
SHOW ENGINES;
SHOW PROCESSLIST命令： 用来展示所有正在运行中的处理线程，这些信息也可以在INFORMATION_SCHEMA的PROCESSLIST表中查到。如果拥有 PROCESS 权限，可以查看所有的线程，否则只能查看自己的线程。
SHOW [FULL] PROCESSLIST;
SHOW [FULL] PROCESSLIST不能查看后台线程的状态，并且会产生锁的性能消耗，performance_schema.threads表中查看不会。
可以使用KILL命令来终止某个线程。
KILL [CONNECTION | QUERY] processlist_id