• mysql(event定时器)


    -- 要查看当前是否已开启事件调度器
    SHOW PROCESSLIST;
    SHOW VARIABLES LIKE 'performance_schema';
    SHOW VARIABLES LIKE 'event_scheduler';
    -- 开启事件调度器
    SET GLOBAL event_scheduler=1 -- 或:SET GLOBAL event_scheduler = ON; 或:my.ini or my.cnf 中的添加 event_scheduler=ON
     
    -- 创建事件(CREATE EVENT)
    /*语法:
    CREATE EVENT [IF NOT EXISTS] event_name
    ON 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}
    */
    -- 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: 等待3秒钟后,再执行查询成功。
    USE readandwrite_test;
    DROP TABLE IF EXISTS `aaa`;
    -- CREATE TABLE aaa (timeline TIMESTAMP);
    CREATE TABLE `aaa` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      timeline TIMESTAMP,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
     
    DROP EVENT IF EXISTS e_test_insert;
    CREATE EVENT e_test_insert
    ON SCHEDULE EVERY 1 SECOND
    DO INSERT INTO readandwrite_test.aaa(timeline) VALUES (CURRENT_TIMESTAMP);
     
    -- 每隔5秒将执行存储过程test,将当前时间更新到aaa表中id=14的记录的timeline字段中去.
    CREATE PROCEDURE test ()
    BEGIN
        update aaa SET timeline = CURRENT_TIMESTAMP WHERE id = 14;
    END;
    CREATE EVENT if not exists e_test
        on schedule every 5 second
        on completion preserve
    do call test();
          
    /** MYSQL取一个月前一个月后的时间
     date_add() 增加
     date_sub()减少
      
     month 月份
     minute 分钟
     second 秒
     例如:select DATE_ADD(NOW(),INTERVAL 1 MONTH); //一个月后的时间
     
    -- ===================================================================================
     
    -- 5天后清空test表:
    CREATE EVENT e_test
    ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 5 DAY
    DO TRUNCATE TABLE readandwrite_test.aaa;
     
    --  2007年7月20日12点整清空test表:
    CREATE EVENT e_test
    ON SCHEDULE AT TIMESTAMP '2007-07-20 12:00:00'
    DO TRUNCATE TABLE readandwrite_test.aaa;
     
    -- 每天定时清空test表:
    CREATE EVENT e_test
    ON SCHEDULE EVERY 1 DAY
    DO TRUNCATE TABLE readandwrite_test.aaa;
     
    -- 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 readandwrite_test.aaa;
     
    -- 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 readandwrite_test.aaa;
     
    -- 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 readandwrite_test.aaa;
     
     
    -- 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 -- [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。
    DO TRUNCATE TABLE readandwrite_test.aaa;
     
    -- 修改事件(ALTER EVENT)
    /*ALTER EVENT event_name
    [ON SCHEDULE schedule]
    [RENAME TO new_event_name]
    [ON COMPLETION [NOT] PRESERVE]
    [COMMENT 'comment']-- 可以给该事件加上注释。
    [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。
    [DO sql_statement]
    */
    -- 临时关闭事件
    ALTER EVENT e_test DISABLE;
    -- 关闭事件任务: alter event e_test ON COMPLETION PRESERVE DISABLE;
     
    -- 开启事件
    ALTER EVENT e_test ENABLE;
    -- 开户事件任务: alter event e_test ON COMPLETION PRESERVE ENABLE;
     
    -- 将每天清空test表改为5天清空一次:
    ALTER EVENT e_test
    ON 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
    */
    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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  • 原文地址:https://www.cnblogs.com/tongxinyuan/p/4443677.html
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