思路: 首先根据最后需求得到的查询包含三个表,推出需要join这三个表然后得到u_n,c_n和date的查询表。 得到该表后,离题目所需答案只差一个“筛选出最近登陆日期”,所以用Windows function追加一列maxdate,然后用筛选条件date=maxdate即可筛选出满足最近登陆日期的 with base as (select *,max(date) over (partition by user_id) as mdate from login) select u.name as u_n,c.name as c_n,b.mdate from user u, client c, ...