php mysql查询前5个平均列

我有一张照片排名表。我想根据3列（评级1、2、3）的平均值输出每个类别前5张照片的id

假设我有以下表格列（photoID、rating1、rating2、rating3）

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默认情况下，MySql中的记录已按升序返回，但您可能希望使用

DESC

关键字，而不是

ASC

。如果您试图选择前5名，为什么要对

评级1

列取平均值

重读问题，重新提交新答案

$sth = "SELECT * FROM pics ORDER BY (rating1 + rating2 + rating3) desc LIMIT 5";

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你解释问题的方式不清楚，这可能是你想要的：

SELECT photoID, AVG((rating1+rating2+rating3)/3) as rating
FROM votes GROUP BY photoID ORDER BY rating DESC LIMIT 5

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表中的类别在哪里？评级1、评级2、评级3是类别。每一行代表一位选民。每张照片可能有10个评分，我想用所有10个评分的平均值找出最高的5个评分。假设我有以下数据photoID 1 rating1 4；类光1比率1；类光2级1 10；类光2比率1 8。我希望输出是photoID 2，然后是photoID 1（即平均等级1分别为9和2.5）

$sth = "SELECT * FROM pics ORDER BY (rating1 + rating2 + rating3) desc LIMIT 5";

SELECT photoID, AVG((rating1+rating2+rating3)/3) as rating
FROM votes GROUP BY photoID ORDER BY rating DESC LIMIT 5

    SELECT 1            AS category
         , photoID
         , AVG(rating1) AS avg_rating
    FROM votes 
    GROUP BY photoID
    ORDER BY avg_rating DESC 
    LIMIT 5

  UNION ALL

    SELECT 2            AS category
         , photoID
         , AVG(rating2) AS avg_rating
    FROM votes 
    GROUP BY photoID
    ORDER BY avg_rating DESC 
    LIMIT 5

  UNION ALL

    SELECT 3            AS category
         , photoID
         , AVG(rating3) AS avg_rating
    FROM votes 
    GROUP BY photoID
    ORDER BY avg_rating DESC 
    LIMIT 5