mysql - 按日期对两个表进行排序和连接

Question

我有以下表格：

posts
post_id | text    | posts_date
1       | blabla  | 06-06-2013
2       | bababa  | 09-06-2013
...

和

comments
comment_id | post_id | user_id | text            | comments_date
1          | 1       | 55      | I like this...  | 06-08-2013
2          | 1       | 66      | Yeah, me also!  | 06-07-2013
3          | 2       | 55      | I like this...  | 06-10-2013
4          | 2       | 66      | Yeah, me also!  | 06-11-2013
...

我需要一个 sql 语句，它返回两个表中的所有列，并首先按posts_date 排序，然后按comments_date 排序。

所以查询的结果表应该是

post_id | text    | posts_date  |  comment_id  | user_id | text            | comments_date
1       | blabla  | 06-06-2013  |   2          | 66      | Yeah, me also!  | 06-07-2013
1       | blabla  | 06-06-2013  |   1          | 55      | I like this...  | 06-08-2013
2       | bababa  | 09-06-2013  |   3          | 55      | I like this...  | 06-10-2013
2       | bababa  | 09-06-2013  |   4          | 66      | Yeah, me also!  | 06-11-2013

我想到了类似的东西

SELECT * FROM comments c, (SELECT * FROM posts ORDER BY posts_date ASC) p WHERE p.post_id = c.post_id ORDER BY comments_date ASC

但这似乎没有给出正确的结果。

Answer 1

SELECT * 
FROM COMMENTS C JOIN POSTS P ON C.post_id = P.post_id 
ORDER BY P.posts_date,C.comments_date ASC

Answer 2

Select * From Posts
inner join Comments on Posts.Post_id = Comments.Post_ID
order by posts.Post_date, comments.comment_date

只会给你带有评论的帖子。

如果您想要帖子，即使他们没有任何评论，那么

Select * From Posts
left join Comments on Posts.Post_id = Comments.Post_ID
order by posts.Post_date, comments.comment_date

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