mysql-定时任务

mysql 定时任务从5.1版本开始引入，又叫做临时触发器，但是与普通触发器不同的是，普通触发器是通过操作数据表的每行数据而触发的事件，而它是通过时间点或者时间周期触发

先来看一下它的语法：

DELIMITER $$ -- SET GLOBAL event_scheduler = ON$$     -- required for event to execute but not create  CREATE /*[DEFINER = { user | CURRENT_USER }]*/ EVENT   `event1` ON SCHEDULE /* uncomment the example below you want to use */ -- scheduleexample 1: run once -- AT 'YYYY-MM-DD HH:MM.SS'/CURRENT_TIMESTAMP { + INTERVAL 1 [HOUR|MONTH|WEEK|DAY|MINUTE|...] } -- scheduleexample 2: run at intervals forever after creation -- EVERY 1 [HOUR|MONTH|WEEK|DAY|MINUTE|...] -- scheduleexample 3: specified start time, end time and interval for execution /*EVERY 1  [HOUR|MONTH|WEEK|DAY|MINUTE|...]

       STARTS CURRENT_TIMESTAMP/'YYYY-MM-DD HH:MM.SS' { + INTERVAL 1[HOUR|MONTH|WEEK|DAY|MINUTE|...] }

       ENDS CURRENT_TIMESTAMP/'YYYY-MM-DD HH:MM.SS' { + INTERVAL 1 [HOUR|MONTH|WEEK|DAY|MINUTE|...] } */ /*[ON COMPLETION [NOT] PRESERVE]
[ENABLE | DISABLE]
[COMMENT 'comment']*/ DO BEGIN (sql_statements) END$$

DELIMITER ;

基本上通过上面的语法说明已经了解到如何使用了，下面针对每种方式可以再写个小栗子

1，在某个时间点触发（执行一次）：

DELIMITER $$ CREATE EVENT `bdhp`.`e_e1` ON SCHEDULE /*只执行一次*/ /*AT '2015-02-03 16:07.00'*//*某一时间点*/ /* AT '2015-02-03 16:47.20' + INTERVAL 40 second*//*某一时间点 + 一段时间*/ AT CURRENT_TIMESTAMP+ INTERVAL 40 SECOND/*当前时间点 + 一段时间*/ DO BEGIN INSERT INTO t_sys_log(sn)VALUES('55555'); END$$

DELIMITER ;

2，按周期执行，无限次数

DELIMITER $$ CREATE EVENT `e_e2` ON SCHEDULE
    
       EVERY 1 MINUTE
DO BEGIN INSERT INTO t_sys_log(sn)VALUES('55555'); END$$

DELIMITER ;

3，在某一时间段内，按周期执行（ends 不写则表示从某一时间点开始执行）

DELIMITER $$ CREATE EVENT `e_e3` ON SCHEDULE
    EVERY 1 SECOND

       STARTS CURRENT_TIMESTAMP ENDS '2015-02-03 16:15.00' DO BEGIN INSERT INTO t_sys_log(sn,USER_NAME)VALUES('test','ttt-55'); END$$

DELIMITER ;