由于项目的业务是不断往前跑的，所以难免数据库的表的量会越来越庞大，不断的挤占硬盘空间。即使再大的空间也支撑不起业务的增长，所以定期删除不必要的数据是很有必要的。在我们项目中由于不清理数据，一个表占的空间竟然达到了4G之多。想想有多可怕...
这里介绍的是用MySQL 建立一个定时器Event，定期清除掉之前的不必要事件。
#1、建立存储过程供事件调用 delimiter// drop procedure if exists middle_proce// create procedure middle_proce() begin DELETE FROM jg_bj_comit_log WHERE comit_time < SUBDATE(NOW(),INTERVAL 2 MONTH); DELETE FROM jg_bj_order_create WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_order_match WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_order_cancel WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_operate_arrive WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_operate_depart WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_operate_login WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_operate_logout WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_operate_pay WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_position_driver WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_position_vehicle WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); DELETE FROM jg_bj_rated_passenger WHERE created_on < SUBDATE(NOW(),INTERVAL 3 MONTH); end// delimiter; #2、开启event(要使定时起作用，MySQL的常量GlOBAL event_schduleer 必须为on 或者1) show variables like ‘event_scheduler‘ set global event_scheduler=‘on‘ #3、创建Evnet事件 drop event if exists middle_event; create event middle_event on schedule every 1 DAY STARTS ‘2017-12-05 00:00:01‘ on completion preserve ENABLE do call middle_proce(); #4、开启Event 事件 alter event middle_event on completion preserve enable; #5、关闭Event 事件 alter event middle_event on completion preserve disable;
原文：http://www.cnblogs.com/jmcui/p/7976569.html