select u.name as u_n,c.name as c_n,l.date
from user as u
inner join login as l
on u.id=l.user_id
inner join client as c
on l.client_id=c.id
where l.date in (select max(date) from login where user_id = l.user_id group by user_id)   --只取每个user最近的login数据
group by u.name
order by u.name   --按name升序


直接排除其他的干扰数据，只要通过子查询筛选每个user最近的一次登录数据，然后直接进行查询