select user.name as u_n,client.name as c_n,max(login.date) as date
from login
inner join user on login.user_id = user.id
inner join client on login.client_id = client.id
group by login.user_id
order by user.name

先联表查询出所需信息，之后分组查询时间最大值（同上一题）