为每个用户ID或昵称列选择一个（最高）分数

Question

我想获得每个用户的最高分，但分数将填入用户ID（INT）或昵称（VARCHAR）列;另一个将为空。

理想情况下会得到这样的结果：

nickname, userid, score
abc, NULL, 1500
NULL, 22, 1250
NULL, 15, 1100
xyz, NULL, 750

Answer 1

SELECT   nickname, userid, MAX(score)
FROM     my_table
GROUP BY nickname, userid

Answer 2

Select COALESCE(nickname, userid) as userid_or_name, max(score) from yourtable
Group by COALESCE(nickname, userid)

Answer 3

SELECT user_id,user_name,MAX(score) FROM user_score
GROUP BY user_id,user_name

see result