SQL查詢將不會執行。無法執行彙總功能

Question

我已經看到有關此問題的其他帖子，但不清楚如何解決該問題。

我相信上次更新聲明是問題所在。我正在嘗試更新RatingValue，這是評分總和除以評分數量的總和。

DELETE 
FROM EasyDNNNewsComments 
WHERE CommentID = 168 

DELETE 
FROM ArticleRating 
WHERE ArticleID = 6605 AND UserID = 10 

UPDATE EasyDNNNews 
SET NumberOfComments = (NumberOfComments - 1) 
WHERE ArticleID = 6605 

UPDATE EasyDNNNews 
SET RatingValue = SUM((SELECT RatingValue 
         FROM ArticleRating 
         WHERE ArticleID = 6605))/
        (SELECT COUNT(*) 
         FROM ArticleRating 
         WHERE ArticleID = 6605) 

Answer 1

你並不需要使用多個查詢此。只需使用聚合作爲數學值。

UPDATE EasyDNNNews 
    SET RatingValue = (SELECT SUM(RatingValue)/COUNT(*) FROM ArticleRating WHERE ArticleID = 6605) 
where ArticleID = 6605 

Answer 2

試試這個：

UPDATE EasyDNNNews 
    SET RatingValue = (SELECT SUM(RatingValue)/COUNT(*) FROM ArticleRating WHERE ArticleID = 6605) 
    WHERE ArticleID = 6605;