使用join mysql从三个表中获取数据

Question

我的数据库中有三个表

1.用户（id,用户名）

2.Stories(id,user_id,content) 这里user_id是外键引用Users表id

3.Comments (id,user_id,story_id,comment) 这里user_id是外来键是指Users表id和story_id是外来键是指Stories表id

我需要从 Stories 表中获取故事列表，其中包含该帖子上的 cmets 总数和故事作者的用户名

这是我的查询

SELECT stories.id,stories.content,COUNT(stories.id) as totalcomment
FROM stories
 JOIN comments
ON stories.id=comments.story_id GROUP BY stories.id

我会得到每个帖子的总评论，但无法获取故事作者的用户名（即用户表中的用户名）

Answer 1

SELECT s.id,s.content,COUNT(c.story_id) as totalcomment, u.username
FROM stories s LEFT JOIN comments c ON (s.id=c.story_id)
LEFT JOIN users u ON (s.user_id = u.id)
GROUP BY s.id

Answer 2

试试这个：

SELECT stories.id,stories.content,COUNT(stories.id) as totalcomment, Users.username
FROM stories, Users, comments
WHERE stories.id=comments.story_id
AND stories.user_id = Users.id
GROUP BY stories.id

或加入：

SELECT stories.id,stories.content,COUNT(stories.id) as totalcomment, Users.username
FROM stories
JOIN comments ON stories.id=comments.story_id
JOIN users ON stories.user_id = Users.id
GROUP BY stories.id

希望这行得通。