Question

如何选择数据库中有喜欢的所有帖子。而且我也希望所有不喜欢的帖子都列在同一个SQL-Query中。喜欢的内容存储在一个表中，每个表都连接到一个带有外键的帖子

SELECT likes.*, posts. * , profile . *, credentials.username, posts.session_sessionid as sSession 
FROM likes, posts, follows, profile, credentials 
WHERE follows.users = posts.userId 
AND profile.userId= follows.users 
AND profile.userId = credentials.profle_userId 
AND posts.session_sessionId IS NOT NULL 
AND likes.idposts = posts.idposts ORDER BY posts.date DESC`

Answer 1

请改用outer join。如果要将like count添加到结果中，一个选项是使用另一个子查询来获取count：

SELECT likes.*, t.likecount, posts.* ,profile.*, credentials.username, 
       posts.session_sessionid as sSession 
FROM posts 
    join follows on follows.users = posts.userId 
    join profile on profile.userId= follows.users 
    join credentials on profile.userId = credentials.profle_userId
    left join likes on likes.idposts = posts.idposts
    left join (
        select idposts, count(*) likecount
        from likes 
        group by idposts
    ) t on t.idposts = posts.idposts
WHERE posts.session_sessionId IS NOT NULL 
ORDER BY posts.date DESC`

一般情况下，我不建议在from子句中使用逗号。

从喜欢和不喜欢的数据库中选择全部

1 个答案: