MySQL的计划任务创建_MySQL

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MySQL的计划任务创建

  实际项目中只想将最近7天的记录保存在MySQL数据库中，使用程序通过SQL指令的方式删除比较麻烦且效率低，用Mysql 提供的事件调度器（event scheduler)可轻松实现。    

具体步骤如下：

1：超级用户方式登陆MySQL console

# mysql　-uroot

2：打开event_scheduler(默认是关掉的）

mysql> set global event_scheduler = ON;

3：创建我们的事件（本例中命名为delete_old_record)    

mysql> CREATE EVENT delete_old_record

　　　ON SCHEDULE EVERY 1 DAY STARTS NOW()

　　　DO

　　　　-- delete the old records of demo_1_table

　　　　DELETE FROM demo_1_table WHERE datediff(NOW(),log_timestamp)>=7;

　　　　-- delete the old records of puma_2_table

　　　　DELETE FROM demo_2_table WHERE datediff(NOW(),log_timestamp)>=7;

　　　　-- delete the old records of puma_3_table

　　　　DELETE FROM demo_3_table WHERE datediff(NOW(),log_timestamp)>=7;

　　　　-- delete the old records of puma_4_table

　　　　DELETE FROM demo_4_table WHERE datediff(NOW(),log_timestamp)>=7;

4：启动创建的事件

mysql> ALTER EVENT delete_old_record ENABLE;

这样以后，数据库就会每天执行DO后面的作业，删除各个table中7天之前的记录。

附录：CREATE EVENT的格式如下：

CREATE

    [DEFINER = { user | CURRENT_USER }]

    EVENT

    [IF NOT EXISTS]

    event_name

    ON SCHEDULE schedule

    [ON COMPLETION [NOT] PRESERVE]

    [ENABLE | DISABLE | DISABLE ON SLAVE]

    [COMMENT 'comment']

    DO event_body;

schedule:

    AT timestamp [+ INTERVAL interval] ...

    | EVERY interval

    [STARTS timestamp [+ INTERVAL interval] ...]

    [ENDS timestamp [+ INTERVAL interval] ...]

interval:

    quantity {YEAR | QUARTER | MONTH | DAY | HOUR | MINUTE |

              WEEK | SECOND | YEAR_MONTH | DAY_HOUR | DAY_MINUTE |

              DAY_SECOND | HOUR_MINUTE | HOUR_SECOND | MINUTE_SECOND}