Question

mysql中每隔一段时间自动执行一次sql语句是怎么回事？

Answer 1

show variables like '%sche%';

set global event_scheduler =1;

update_a 

mysql> create procedure update_a() update a set a.y_avg=(select avg(b.youhao) from b where a.a_id=b.a_id);

event e_updateA

mysql> create event if not exists e_updateA

-> on schedule every 60 second 

-> on schedule at date_add(now(),interval 1 minute) 

-> on completion preserve

-> do call update_a(); 

mysql> alter event e_updateA ON

-> COMPLETION PRESERVE DISABLE

mysql> alter event e_updateA ON

-> COMPLETION PRESERVE ENABLE;