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MySQL计划任务(事件调度器) Event Scheduler介绍

来源:http://www.soniaLorenzana.com 作者:493333王中王开奖结果 时间:2020-03-28 06:12

要查看当前是否已开启事件调度器,可执行如下SQL:

SHOW VARIABLES LIKE 'event_scheduler';或

SELECT @@event_scheduler;或

SHOW PROCESSLIST;若显示:

+-----------------+-------+| Variable_name | Value |+-----------------+-------+| event_scheduler | OFF |+-----------------+-------+则可执行

SET GLOBAL event_scheduler = 1;或

SET GLOBAL event_scheduler = ON;来开启,也可以直接在启动命令加上“–event_scheduler=1”,例如:

mysqld ... --event_scheduler=1

my.ini or my.cnf 中的[mysqld]添加 event_scheduler=ON

创建事件(CREATE EVENT)先来看一下它的语法:

CREATE EVENT [IF NOT EXISTS] event_nameON SCHEDULE schedule[ON COMPLETION [NOT] PRESERVE][ENABLE | DISABLE][COMMENT 'comment']DO sql_statement;

schedule:AT TIMESTAMP [+ INTERVAL INTERVAL]| EVERY INTERVAL [STARTS TIMESTAMP] [ENDS TIMESTAMP]

INTERVAL:quantity {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE | WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE | DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}

1)首先来看一个简单的例子来演示每秒插入一条记录到数据表

USE test;CREATE TABLE aaa (timeline TIMESTAMP);CREATE EVENT e_test_insertON SCHEDULE EVERY 1 SECOND DO INSERT INTO test.aaa VALUES (CURRENT_TIMESTAMP);等待3秒钟后,再执行查询成功。2) 5天后清空test表:CREATE EVENT e_testON SCHEDULE AT CURRENT_TIMESTAMP

  • INTERVAL 5 DAYDO TRUNCATE TABLE test.aaa;3) 2007年7月20日12点整清空test表:

CREATE EVENT e_testON SCHEDULE AT TIMESTAMP '2007-07-20 12:00:00'DO TRUNCATE TABLE test.aaa;4) 每天定时清空test表:

CREATE EVENT e_testON SCHEDULE EVERY 1 DAYDO TRUNCATE TABLE test.aaa;5) 5天后开启每天定时清空test表:

CREATE EVENT e_testON SCHEDULE EVERY 1 DAYSTARTS CURRENT_TIMESTAMP + INTERVAL 5 DAYDO TRUNCATE TABLE test.aaa;6) 每天定时清空test表,5天后停止执行:

CREATE EVENT e_testON SCHEDULE EVERY 1 DAYENDS CURRENT_TIMESTAMP + INTERVAL 5 DAYDO TRUNCATE TABLE test.aaa;7) 5天后开启每天定时清空test表,一个月后停止执行:

CREATE EVENT e_testON SCHEDULE EVERY 1 DAYSTARTS CURRENT_TIMESTAMP + INTERVAL 5 DAYENDS CURRENT_TIMESTAMP + INTERVAL 1 MONTHDO TRUNCATE TABLE test.aaa;[ON COMPLETION [NOT] PRESERVE]可以设置这个事件是执行一次还是持久执行,默认为NOT PRESERVE。8) 每天定时清空test表(只执行一次,任务完成后就终止该事件):

CREATE EVENT e_testON SCHEDULE EVERY 1 DAYON COMPLETION NOT PRESERVEDO TRUNCATE TABLE test.aaa;[ENABLE | DISABLE]可是设置该事件创建后状态是否开启或关闭,默认为ENABLE。[COMMENT ‘comment']可以给该事件加上注释。

修改事件(ALTER EVENT)ALTER EVENT event_name[ON SCHEDULE schedule][RENAME TO new_event_name][ON COMPLETION [NOT] PRESERVE][COMMENT 'comment'][ENABLE | DISABLE][DO sql_statement]1) 临时关闭事件

ALTER EVENT e_test DISABLE;2) 开启事件

ALTER EVENT e_test ENABLE;3) 将每天清空test表改为5天清空一次:

ALTER EVENT e_testON SCHEDULE EVERY 5 DAY;

删除事件(DROP EVENT)语法很简单,如下所示:

DROP EVENT [IF EXISTS] event_name例如删除前面创建的e_test事件

DROP EVENT e_test;当然前提是这个事件存在,否则会产生ERROR 1513 (HY000): Unknown event错误,因此最好加上IF EXISTS

DROP EVENT IF EXISTS e_test;

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