MySQL的：SUM 3個記錄每

Question

類別

我有下面的表：

dayoftheweek (VARCHAR) 
player (VARCHAR) 
score (INT) 

對於每個播放器，有或者3，4或5的分數。 我必須計算每位玩家每週最佳3分的平均值。

我正沿

SELECT dayoftheweek, player, (SUM(score)/3) AS average_score 
FROM (SELECT dayoftheweek, player, score 
     FROM scoretable 
     GROUP BY dayoftheweek, player 
     ORDER BY score 
     LIMIT 0, 3) AS query 

但（顯然），只有給我的前三個記錄總體思路思考.. 有人可以把我在正確的方向嗎？

乾杯，馬塞爾

Answer 1

你應該能夠編寫：

SELECT dayoftheweek, 
     player, 
     (SELECT AVG(score) 
      FROM (SELECT inner.score 
        FROM scoretable AS inner 
        WHERE inner.dayoftheweek = outer.dayoftheweek 
        AND inner.player = outer.player 
        ORDER 
         BY inner.score DESC 
        LIMIT 3 
       ) 
     ) AS best_score_avg 
    FROM scoretable AS outer 
; 

（免責聲明：沒有測試）

請注意，我用ORDER BY ... DESC拿到三個最大得分，但如果這些是高爾夫分數或者其中最好的分數是至少那些，那麼您將想要將DESC更改爲ASC（或只是刪除它）。