使用 Left Join 和Where IN 子句的 MYSQL 查询

Question

我有三个表 A B C，我正在尝试从这三个表中检索信息。

A 具有列 userid 头像用户名，B 具有列 postid, dateshared，C 具有列评论者 postid datecommented。

我正在尝试运行查询

Select  C.comment, C.commenter,  C.datecommented, B.postid, B.dateshared A.username A.avatar from B Left Join C  Left join A on C.postid = B.postid AND A.userid = C.commenter where B.postid IN ('1','2','3') order by  C.dateshared desc

但它给出了以下错误:

 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where B.postid IN ('1', '2', '3') order by C.dateshared '

任何人都可以指出我做错了什么或建议如何解决吗？

Answer 1

每个 LEFT JOIN 都需要自己的 ON 条件:

SELECT  C.comment, C.commenter, C.datecommented, B.postid, B.dateshared, A.username A.avatar
FROM    B
LEFT JOIN
        C
ON      C.postid = B.postid
LEFT JOIN
        A
ON      A.userid = C.commenter
WHERE   B.postid IN ('1','2','3')
ORDER BY
        C.dateshared desc