Question

我想在mysql中创建一个表，该表有3列user_id，activity - online或offline - 和timestamp，现在我希望该表显示所有user_id以及最新状态。目前正在使用

 SELECT DISTINCT user_id,activity FROM activity ORDER BY timestamp DESC

语句显示用户上次上线和离线的时间，这不是我想要的。

Answer 1

select user_id, max(timestamp) ts from activity a
inner join
   (select user_id, activity, max(timestamp) ts
   group by user_id, activity) iam
on iam.user_id =a.user_id and a.ts = iam.ts

Answer 2

试试这个：

 select act.*
 from activity as act
      inner join (
          select user_id, max(timestamp) as max_ts
          from activity
          group by user_id) as a on act.user_id=a.user_Id and act.timestamp=a.max_ts

这将返回每个用户的最新记录。

mysql查询最近的记录

2 个答案: