public Leaf(string name) : base(name) { }
public override void Add(Component c)
{
Console.WriteLine("Cannot add to a leaf")
}
public override void Remove(Component c)
{
Console.WriteLine("Cannot remove to a leaf")
}
public override void Display(int depth)
{
Console.WriteLine(new string('-',depth)+name)
}
}
mysql的定时任务一般用event(事件)来完成,触发器无法完成。一、通过mysql的命令行客户端来完成
1、set global event_scheduler =1//开启event_scheduler
执行这个语句如果出现,可在mysql的配置文档中设置[mysqld]段中添加 event_scheduler=ON
如果重启mysql;这种情况下依然出错,Error Code: 1290. The MySQL server is running with the --event-scheduler=DISABLED
or --skip-grant-tables option so it cannot execute this statement,这个错误是说启动服务器时如果指定了--skip-grant-tables选项,则event_scheduler则自动被设置为DISABLED。命令行或配置文件的设置都会被覆盖。建议重现安装mysql或是修改启动参数(在系统服务中指定)。
查看event_scheduler状态:show status like '%event%'或SELECT @@event_scheduler
2、CREATE PROCEDURE Mypro() //创建存储过程
BEGIN
update userinfo SET endtime = now() WHERE id = '155'
END
3、创建event My_enevt,每隔三十秒执行一次
create event if not exists e_test
on schedule every 30 second
on completion preserve
do call Mypro()
4、关闭事件
alter event e_test ON COMPLETION PRESERVE DISABLE
5、开启事件
alter event e_test ON COMPLETION PRESERVE ENABLE
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}
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