1.先查询每个用户的最近登录日期
select user_id,max(date) from login group by user_id2、查询最近登录日期的用户的全部信息(用户id,设备id,日期)
select user_id,client_id,date from login where (user_id,date) in (select user_id,max(date) from login group by user_id)3、将user表和2表及client表join,并按user的name 排序
select a.name as u_n,c.name as c_n, b.date from user as a join (select user_id,client_id,date from login where (user_id,date) in (select user_id,max(date) from login group by user_id) ) as b on a.id=b.user_id join client as c on b.client_id=c.id order by a.name;