题解 | #牛客每个人最近的登录日期(二)#

with tmp as (
    select user_id, max(date) as lastday from login
    group by user_id
    order by user_id
)

select u.name, c.name, lastday from user u 
inner join login l on u.id = l.user_id
inner join client c on l.client_id = c.id 
inner join tmp t on t.user_id = l.user_id
where l.date = t.lastday
group by u.name, c.name, lastday
order by u.name

连接后用where做一个过滤

没搞明白group by 为什么跟了三个东西都过了