mysql 常用sql

-- number 为字符串，且第一位为字母，排序

SELECT CONCAT(SUBSTRING(number,1,1),LPAD(MID(number,2,10) ,2,'0')),number FROM tableA WHERE cabinet_id = '2b3482a570804f6f982ef8bcb97d6434' ORDER BY CONCAT(SUBSTRING(number,1,1),LPAD(MID(number,2,10) ,2,'0')) ASC;

 -- 数据库连接依据ip分组

SELECT SUBSTRING_INDEX(HOST,':',1) AS ip , COUNT(*) FROM information_schema.processlist GROUP BY ip;

-- 查询所有的列

INFORMATION_SCHEMA.COLUMNS 

-- 查询所有的表

INFORMATION_SCHEMA.TABLES