mysql - 复合mysql查询异常问题

Question

假设有以下三个表:

• td_idea

  +----------+--------------+----------------------+------------------+
  | idea_id  |  idea_name   |  idea_submitter_id   |   idea_status    |
  +----------+--------------+----------------------+------------------+
  | 1        |  shirt       |           3          |   Design         |
  | 2        |  top         |           1          |   Color          |
  +----------+--------------+----------------------+------------------+
  

• td_idea_contribution

  +------------------+------------+-----------------+
  | contribution_id  |  idea_id   |  submitter_id   |
  +------------------+------------+-----------------+
  |        1         |      1     |        3        |
  |        2         |      1     |        4        |
  |        3         |      1     |        7        |
  |        4         |      1     |        10       |
  |        5         |      2     |        3        |
  |        6         |      2     |        10       |
  +------------------+------------+-----------------+
  

  This table shows the contribution that users have made on a particular idea.

• td_idea_contribution_like

  +----------+--------------------+-----------------+
  | like_id  |  contribution_id   |  submitter_id   |
  +----------+--------------------+-----------------+
  |     1    |          1         |        1        |
  |     2    |          1         |        4        |
  |     3    |          2         |        24       |
  |     4    |          1         |        73       |
  |     5    |          4         |        124      |
  |     6    |          2         |        34       |
  |     7    |          1         |        75       |
  |     8    |          3         |        124      |
  +----------+--------------------+-----------------+
  

I want to display all the contributions for a particular idea_id, each showing the number of votes for each contribution listed.

So, for idea_id = 1, I wish to see the following output:

+------------------+------------------+--------------+
|  contribution_id |    total_likes   |    user_id   |
+------------------+------------------+--------------+
|        1         |        4         |      3       |
|        2         |        2         |      4       |
|        3         |        1         |      7       |
|        4         |        1         |     10       |
+------------------+------------------+--------------+

I am currently using the following query, but weird results are being displayed:

SELECT   td_idea.idea_id,
         td_idea_contribution.contributuion_id,
         td_idea_contribution.submitter_id,
         COUNT(td_idea_contribution_like.contribution_like_id) AS tot_like
FROM     td_idea, td_idea_contribution, td_idea_contribution_like
WHERE    td_idea.idea_id = td_idea_contribution.idea_id 
     AND td_idea_contribution.contribution_id = td_idea_contribution_like.contribution_id
     AND td_idea.idea_id = '$id'
     AND td_idea.status LIKE '%Design%'
ORDER BY tot_like DESC

<小时/>

编辑

我没有收到错误，我只是收到包含一条记录的异常结果，如下所示:

+------------------+------------------+--------------+
|  contribution_id |    total_likes   |    user_id   |
+------------------+------------------+--------------+
|        1         |        8         |      3       |
+------------------+------------------+--------------+

Answer 1

如 GROUP BY (Aggregate) Functions 下所述:

If you use a group function in a statement containing no GROUP BY clause, it is equivalent to grouping on all rows.

这就是您的情况所发生的情况。为了防止这种情况，您需要按 contribution_id 对结果进行分组:

SELECT   contribution_id,
         COUNT(*) AS total_likes,
         c.submitter_id AS user_id
FROM     td_idea                   i
    JOIN td_idea_contribution      c USING (        idea_id)
    JOIN td_idea_contribution_like l USING (contribution_id)
WHERE    idea_id = 1
     AND idea_status LIKE '%Design%'
GROUP BY contribution_id
ORDER BY total_likes DESC

查看 sqlfiddle .