trigger向一个表插入数据，并按照一定条件更新另外一个表。

向au_online_info插入一条记录，如果au_online_total表中存在相同userid的记录，则total_online，total_score累加online_time，如果不存在就向表au_online_total中一条记录（total_online，total_score为相同值）。

Create Table: CREATE TABLE `au_online_info` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userid` bigint(20) NOT NULL,
  `username` varchar(50) NOT NULL,
  `login_time` datetime NOT NULL,
  `logout_time` datetime NOT NULL,
  `online_time` float NOT NULL,
  `login_ip` varchar(50) DEFAULT NULL,
  `memo` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1


Create Table: CREATE TABLE `au_online_total` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userid` bigint(20) NOT NULL,
  `username` varchar(50) NOT NULL,
  `total_online` bigint(20) NOT NULL,
  `total_score` bigint(20) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1



delimiter //
create trigger au_online_info_total after insert on au_online_info for each row
Begin
set @userid:=new.userid;
set @online_time:=new.online_time;
If not exists(select 1 from au_online_total where userid= @userid) then
insert into au_online_total(userid,username,total_online,total_score) select userid,username,sum(online_time),sum(online_time) from au_online_info where userid=@userid;
else
update au_online_total set total_online=total_online @online_time,total_score=total_score @online_time where userid=@userid;
END IF;
end;
//
delimiter ;

insert into au_online_info(userid,username,online_time) values(2,'jack2',1) ;