从一个表中选择计数，然后根据一个ID加入另一个表

Question

现在我有这个查询：

SELECT s.*, u.username,
FROM submissions s
JOIN users u ON s.user_id
WHERE s.id = 15

这给了我：

*************************** 1. row ***************************
         id: 15
      title: dsaffdsadfsafds
       slug: dsaffdsadfsafds
description: dfsdfsdfsafadsdfasdfs
    user_id: 15
    created: 2014-01-12 14:21:29
   category: autos-vehicles
       type: request
  thumbnail:
    removed: 0
   keywords: dsaffdsadfsafds
         ip: 127001
   username: blahbster

现在，我想从另一个名为submissions_votes表中添加一个计数。

SELECT count(id) as "submissionVotes"
FROM submissions_votes
WHERE submission_id = 15

我试图将它们合并如下：

SELECT s.*, u.username, 
  (SELECT count(id)
  FROM submissions_votes
  WHERE submission_id = 15) as "submissionVotes",
FROM submissions s
JOIN users u ON s.user_id
WHERE s.id = 15;

但是我遇到了错误。 在这里需要帮助...

Answer 1

尝试：

SELECT s.*, u.username, COUNT(sv.id) votes FROM submissions s INNER JOIN users u ON 
s.user_id = u.id LEFT JOIN submissions_votes sv ON s.id = sv.submission_id 
WHERE s.id = 15 GROUP BY sv.submission_id