有用的SQL

清空数据库全部表：

SELECT CONCAT('truncate TABLE ',table_schema,'.',TABLE_NAME,';') FROM INFORMATION_SCHEMA.TABLES WHERE table_schema IN ('db_name');

备注：执行上述语句会批量生成清空语句，然后需要手动执行批量清空语句。

 

获取数据库全部表结构：

SELECT * FROM COLUMNS WHERE TABLE_SCHEMA NOT IN ('information_schema','performance_schema','mysql','sys');

 

格式化时间戳并按日统计数据：

SELECT FROM_UNIXTIME(created_at,"%Y%m%d") AS udate, count(1) AS unum FROM table_name GROUP BY udate;