【MySQL】MIN()、MAX()比较日期大小
思路：注意题目的两个关键词，每位玩家，所以用GROUP BY
第一次的日期，所以用MIN(DATE)
SELECT player_id,
MIN(event_date) AS `first_login`
FROM Activity AS a
GROUP BY player_id;
这种很方便，不过窗口函数会快点
SELECT s.player_id,
s.event_date AS `first_login`
FROM (
SELECT a.player_id,
a.event_date,
ROW_NUMBER() OVER (
PARTITION BY a.player_id
ORDER BY a.event_date
) AS n
FROM Activity AS a
) AS s
WHERE s.n = 1;
或者这么写
SELECT DISTINCT a.player_id,
FIRST_VALUE(a.event_date) OVER (
PARTITION BY
a.player_id
ORDER BY
a.event_date
) AS first_login
FROM
Activity AS a;
原文地址：https://blog.csdn.net/lklalmq/article/details/145097080
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