Question

我有一个名为meeting的表，还有一个名为meeting_permissions的表。后者存储用户参加任何特定会议的内容。我还有其他表格：注释，讨论，结论和主题，用于存储该会议成绩单的特定项目。我想做的是获得特定用户参与的所有会议，以及所有相关的注释，讨论，结论和主题。这就是我想出的：

SELECT * FROM meeting WHERE id IN
(SELECT meeting_id FROM meeting_permissions WHERE user_id = $user) 
LEFT JOIN conclusion ON meeting.id = conclusion.meeting_id 
LEFT JOIN discussion ON meeting.id = discussion.meeting_id 
LEFT JOIN note ON meeting.id = note.meeting_id 
LEFT JOIN topic ON meeting.id = topic.meeting_id

这对我不起作用。它打破了第二个左连接。我该怎么做才能解决这个问题？

Answer 1

您加入了您的子选择而不是主会议桌：

SELECT 
  meeting.*,
  conclusion.*
  discussion.*,
  note.*,
  topic.*
FROM meeting 
  LEFT JOIN conclusion ON meeting.id = conclusion.meeting_id 
  LEFT JOIN discussion ON meeting.id = discussion.meeting_id 
  LEFT JOIN note ON meeting.id = note.meeting_id 
  LEFT JOIN topic ON meeting.id = topic.meeting_id
WHERE meeting.id IN
  (SELECT mp.meeting_id FROM meeting_permissions mp WHERE mp.user_id = $user)

从多个子表中选择

1 个答案: