# 查询每个用户最近登录的一天及其使用的客户端id
with t1 as(
    select user_id, client_id, `date`
    from login
    where (user_id, `date`) in (
        select user_id, max(`date`) m_date
        from login 
        group by user_id
    )
)

select u.name u_n, c.name c_n, `date`
from t1
join user u
on t1.user_id=u.id
join client c
on t1.client_id=c.id
order by u_n;