Question

它在上面的SQL查询中返回第6级而不是第1级。我需要在SQL查询中进行哪些更改，因此它提供了第一个等级，因为我使用WHERE条件来检查mpkid和roundpkid（WHERE mpkid = 37 AND roundpkid = 3）。

以下是查询：

SELECT mpkid, totalvote, rank 
FROM ( 
 SELECT mpkid, roundpkid, totalvote, 
 @n := IF(@g = totalvote, @n, @n + 1) rank, 
 @g := totalvote 
 FROM tr_msearch_vote_summary, 
 (SELECT @n := 0) i 
 ORDER BY totalvote DESC 
) q 
WHERE mpkid=37 AND roundpkid=3

我想要的是什么：

请先看看sqlfiddle。第3轮只有一个记录，它是37，所以我希望它应该显示mpkid＃37和＃3轮排名＃1，但它排名第6。

Answer 1

您在排名已完成后应用WHERE条件。我猜你想在WHERE应用后进行排名：

  SELECT t.mpkid, t.roundpkid,  
         @n := IF(@g = t.totalvote, @n, @n + 1) rank,
         @g := t.totalvote totalvote
    FROM tr_msearch_vote_summary t, (SELECT @n := 0) i 
   WHERE t.mpkid=37 AND t.roundpkid=3
ORDER BY t.totalvote DESC

您还应该初始化@g以确保它不会在另一个查询中预设：

  SELECT t.mpkid, t.roundpkid,  
         @n := IF(@g = t.totalvote, @n, @n + 1) rank,
         @g := t.totalvote totalvote
    FROM tr_msearch_vote_summary t, (SELECT @n := 0, @g := NULL) i 
   WHERE t.mpkid=37 AND t.roundpkid=3
ORDER BY t.totalvote DESC

<强>更新

如果你想要按轮次分组，然后简单地按照mpkid进行选择，这是一个更强大的查询：

SELECT mpkid,
       roundpkid,
       totalvote,
       rank
  FROM (
    SELECT t.mpkid,  
           @n := CASE 
                   WHEN @r = t.roundpkid AND @g = t.totalvote THEN @n
                   WHEN @r = t.roundpkid THEN @n + 1
                   ELSE 1
                 END rank,
           @r := t.roundpkid roundpkid,
           @g := t.totalvote totalvote
      FROM tr_msearch_vote_summary t, (SELECT @n := 0, @g := NULL, @r := NULL) i 
  ORDER BY t.roundpkid, t.totalvote DESC
       ) r
 WHERE mpkid = 37;

请注意，您无需提供roundpkid。 See updated fiddle

Answer 2

请尝试此查询，

SELECT mpkid, totalvote, rank 
FROM ( 
  SELECT mpkid, roundpkid, totalvote, 
  @n := IF(@g = totalvote, @n, @n + 1) rank, 
  @g := totalvote 
  FROM tr_msearch_vote_summary, 
  (SELECT @n := 0) i 
WHERE roundpkid=3
ORDER BY totalvote DESC 
) q 
WHERE mpkid=37

这是你更新的sqlfiddle。 http://sqlfiddle.com/#!9/083f5d/9

在mySQL中使用WHERE子句获得不正确的排名

2 个答案: