Question

我需要获取论坛名称，帖子名称和帖子ID为32的帖子。

这可以用1个查询吗？

论坛

ID
名称

线程

ID
forumid
受试者

帖子

ID
线程ID
消息

Answer 1

SELECT f.name, t.subject, p.message
FROM posts AS p
INNER JOIN threads AS t
  ON p.threadid = t.id
INNER JOIN forums AS f
  ON t.forumid = f.id
WHERE p.id = 32

Answer 2

select * 
from forums f 
     join threads t on f.id = t.forumid 
     join posts p on p.threadid = threads.id 
where p.id = 32

Answer 3

有什么问题？

select name, subject, message from posts join threads on (threadid=posts.id) join forums on (forumid=forums.id) where posts.id=32

Answer 4

我添加了帖子的ID以查看行

SELECT p.id ,p.message,t.subject, f.name
FROM forums AS f
RIGHT OUTER JOIN threads AS t
ON f.id = t.forumid
RIGHT OUTER JOIN posts AS p
ON t.id = p.threadid
WHERE p.id = 32

在MySql上测试

硬连接。可能吗？

4 个答案: