mysql SELECT在单个表中每个类别的最佳选择 [英] mysql SELECT best of each category in a single table

问题描述

说我有一个叫Gamers的桌子. 游戏玩家包含列GamerID，GameID，Score.

Lets say I have a table called Gamers. Gamers contains the columns GamerID, GameID, Score.

我有兴趣选择每场得分最高的球员.

I am interested in selecting the highest scoring player of each game.

例如，

|Gamers
|-------------------------
|GamerID | GameID | Score
|1       | 1      | 10
|2       | 1      | 10
|3       | 1      | 10
|4       | 1      | 90
|5       | 2      | 40
|6       | 2      | 10
|7       | 3      | 10
|8       | 3      | 30

查询后，我希望获取GamerID 4、5和8的行.执行该操作的查询是什么?

After the query, I hope to get the rows for GamerID 4, 5 and 8. What is the query that would do this?

推荐答案

尝试一下:

SELECT gamers.*
FROM gamers
INNER JOIN 
 (SELECT 
   max(score) as maxscore, 
   gameid from gamers
   GROUP BY gameid) AS b
ON (b.gameid = gamers.gameid AND b.maxscore=gamers.score) ;
ORDER BY score DESC, gameid;

这将输出:

+---------+--------+-------+
| gamerid | gameid | score |
+---------+--------+-------+
|       4 |      1 |    90 |
|       5 |      2 |    40 |
|       8 |      3 |    30 |
+---------+--------+-------+
3 rows in set (0.00 sec)

您可以执行的另一种选择是创建临时表或视图(如果您不喜欢子查询).

The other option you can do is to create a temporary table or a view (if you don't like sub-query).

create temporary table games_score (
 SELECT max(score) as maxscore, gameid FROM gamers GROUP BY gameid
);

然后:

SELECT gamers.* 
FROM gamers 
INNER JOIN games_score AS b ON (b.gameid = gamers.gameid AND b.maxscore=gamers.score) 
ORDER BY score DESC, gameid;

或视图:

create or replace view games_score AS 
SELECT max(score) as maxscore, gameid FROM gamers GROUP BY gameid;

然后:

SELECT gamers.* 
FROM gamers 
INNER JOIN games_score AS b ON (b.gameid = gamers.gameid AND b.maxscore=gamers.score) 
ORDER BY score DESC, gameid;

这篇关于mysql SELECT在单个表中每个类别的最佳选择的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！