MySql-使用事件调度器(event_scheduler)

写在前面：

MySql版本要高于5.1

0. 开启服务

SHOW VARIABLES LIKE 'event_scheduler';

+-----------------+-------+

| Variable_name | Value |

+-----------------+-------+

| event_scheduler | OFF |

+-----------------+-------+

1 row in set

默认没有开启

使用 SET GLOBAL event_scheduler = 1;

或者 SHOW VARIABLES LIKE 'event_scheduler';

+-----------------+-------+

| Variable_name | Value |

+-----------------+-------+

| event_scheduler | ON |

+-----------------+-------+

1 row in set

1. 实际需求

系统中有一个模块需要从多个视图中根据用户名取数据，加载到首页，因为刷新首页比较耗时，所以新建一张绩效表，专门存这些数据，而即时更新这张表的值，就交给了事件调度器来做了。

2. SQL语法(官网)

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}

[ON COMPLETION]：执行完之后是否保留当前event

[ENABLE | DISABLE | DISABLE ON SLAVE]：创建后启用还是不启用

3. 示例

create event e_update_test
on schedule every 10 second
starts current_timestamp
on completion preserve enable
do
update test_table set num = num + 1;

创建一个事件调度器，名字为e_update_test，从创建完后每10秒执行一次，并且执行完不删除，执行内容为 更新test_table表的num字段，每次更新都加一

而用Navicat for MySql创建，图形化界面更直观也更简单一些：

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