MySql中的定时器

实例1：

/*开启功能*/
SET GLOBAL event_scheduler = ON;
 
DELIMITER //
DROP EVENT IF EXISTS `eventlog`;
CREATE    EVENT IF NOT EXISTS `eventlog`
 
ON SCHEDULE
EVERY 1 DAY 
 STARTS TIMESTAMP(CURRENT_DATE,'09:00:00')
 ON COMPLETION PRESERVE ENABLE
DO
    BEGIN
        DELETE FROM TAB_LOG WHERE TAB_LOG.DT_TIME < DATE_ADD(NOW(),INTERVAL "0" DAY);
    END;
//
DELIMITER ;

实例2：

创建event My_enevt,每隔三十秒执行一次

create event if not exists e_test
on schedule every 30 second
on completion preserve
do call Mypro();

实例3：

DROP EVENT
IF EXISTS update_tmpTable;

create event if not exists update_tmpTable
on schedule EVERY 1 DAY STARTS TIMESTAMP (CURRENT_DATE, '10:13:00') 
on completion preserve
do DROP TABLE IF EXISTS tmp_table;
alter event update_tmpTable ON COMPLETION PRESERVE ENABLE;

实例4：

DROP EVENT
IF EXISTS create_tmpTable;

create event if not exists create_tmpTable
on schedule EVERY 1 DAY STARTS TIMESTAMP (CURRENT_DATE, '10:19:00') 
on completion preserve
do 
CREATE table temp_table ENGINE = MEMORY
select * from user;
alter event create_tmpTable ON COMPLETION PRESERVE ENABLE;

实例5：

    /*开启功能*/  
    SET GLOBAL event_scheduler = ON;  
       
    DELIMITER //  
    DROP EVENT IF EXISTS `eventlog`;  
    CREATE EVENT IF NOT EXISTS `eventlog`  
       
    ON SCHEDULE  
    EVERY 1 DAY   
     STARTS TIMESTAMP(CURRENT_DATE,'14:50:00')  
     ON COMPLETION PRESERVE ENABLE  
    DO  
        BEGIN  
            DROP TABLE IF EXISTS temp_table;
						CREATE table temp_table ENGINE = MEMORY
						select * from user;
        END;  
    //  
    DELIMITER ;  

关闭事件：

alter event e_test ON COMPLETION PRESERVE DISABLE;

开启事件：

alter event e_test ON COMPLETION PRESERVE ENABLE;

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
CREATE EVENT e_test_insert ON SCHEDULE EVERY 1 SECOND DO INSERT INTO test.aaa VALUES  (CURRENT_TIMESTAMP);

2) 5天后清空test表：
CREATE EVENT e_test ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 5 DAY DO TRUNCATE TABLE test.aaa;

3) 2013年7月20日12点整清空test表：
CREATE EVENT e_test ON SCHEDULE AT TIMESTAMP '2013-07-20 12:00:00' DOTRUNCATE TABLE test.aaa;

4) 每天定时清空test表：
CREATE EVENT e_test ON SCHEDULE EVERY 1 DAY DO TRUNCATE TABLE test.aaa;

5) 5天后开启每天定时清空test表：
CREATE EVENT e_test ON SCHEDULE EVERY 1 DAY STARTS CURRENT_TIMESTAMP + INTERVAL 5 DAY DO TRUNCATE TABLE test.aaa;

6) 每天定时清空test表，5天后停止执行：
CREATE EVENT e_test ON SCHEDULE EVERY 1 DAY ENDS CURRENT_TIMESTAMP + INTERVAL 5 DAY DO 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_test ON SCHEDULE EVERY 1 DAY STARTS CURRENT_TIMESTAMP +
INTERVAL 5 DAY ENDS CURRENT_TIMESTAMP + INTERVAL 1 MONTH DO 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_test ON SCHEDULE EVERY 1 DAY ON COMPLETION NOT PRESERVE DO TRUNCATE TABLE test.aaa;

[COMMENT
comment]可以给该事件加上注释

2>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_test ON SCHEDULE EVERY 5 DAY;

3>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;