Mysql 定时器
直接代码：
# 开启定时器支持
show variables like '%sche%';
set global event_scheduler =1;
# 创建定时器 30秒执行一次
create event if not exists startExam
on schedule every 30 second
on completion preserve
do call updExamStartTimeAndEndTime(); # 调用存储过程
-- 开启
alter event startExam ON
COMPLETION PRESERVE ENABLE;
-- 关闭
alter event startExam ON
COMPLETION PRESERVE DISABLE;