题目链接：点击打开链接
题目大意：略。
解题思路：略。
AC 代码
-- 解决方案(1) SELECT user_id AS 'user_id', MAX(time_stamp) AS 'last_stamp' FROM Logins WHERE YEAR(time_stamp) = '2020' GROUP BY user_id; -- 解决方案(2) SELECT user_id, time_stamp last_stamp FROM (SELECT user_id, time_stamp, RANK() OVER(PARTITION BY user_id ORDER BY time_stamp DESC) rk FROM Logins WHERE YEAR(time_stamp) = '2020') t WHERE rk = 1
