Question

我有2张桌子

主表

Id_post
Id_user_post
Post
Date_post

辅助表

Id_mentioned
Id_user
Id_user_post
Id_post
Date_mentioned

例如，我有13个记录第一个表，3个记录第二个。

第一张表记录（13）

1 herman this is text 1 10:00:00 15/09/2016
2 jhon this is text 2 11:00:00 15/09/2016
3 carl this is text 3 12:00:00 15/09/2016
4 herman this is text 4 13:00:00 15/09/2016
5 herman this is text 5 14:00:00 15/09/2016
6 herman this is text 6 15:00:00 15/09/2016
7 jhon this is text 7 16:00:00 15/09/2016
8 herman this is text 8 17:00:00 15/09/2016
9 herman this is text 9 18:00:00 15/09/2016
10 carl this is text 10 19:00:00 15/09/2016
11 herman this is text 11 20:00:00 15/09/2016
12 carl this is text 12 21:00:00 15/09/2016
13 herman this is text 13 22:00:00 15/09/2016

第二个表记录

1 herman jhon 7 11:20:00 15/09/2016
2 jhon carl 10 12:30:00 15/09/2016
3 herman carl 3 14:50:00 15/09/2016

如果我选择赫尔曼的帖子，我想要下一个结果，按日期排序（发布日期和提及的日期）

1 herman this is text 1 10:00:00 15/09/2016
7 jhon   this is text 7 11:20:00 15/09/20167 (date mentioned)
4 herman this is text 4 13:00:00 15/09/2016
5 herman this is text 5 14:00:00 15/09/2016
3 carl   this is text 3 14:50:00 15/09/2016 (date mentioned)
6 herman this is text 6 15:00:00 15/09/2016
8 herman this is text 8 17:00:00 15/09/2016
9 herman this is text 9 18:00:00 15/09/2016
11 herman this is text 11 20:00:00 15/09/2016
13 herman this is text 13 22:00:00 15/09/2016

在这些结果中出现了由hermman提交的帖子和第二个表中提到的帖子，由date_tioned排序（其中像twitter一样在配置文件中，在主要结果中显示自己的帖子和不属于同一个人的retwitts所有者）

我试过sql join left

Select * from $table_posts left join $table_mentions on $table_posts.id_user=$table_mentions.id_user order by date_post,date_mentioned

我也尝试过，但没有...

SELECT * FROM $table_posts WHERE id_user_post=(SELECT id_user_post FROM $table_mentions WHERE id_user_post='$id_user') AND id_user_post='$id_user'  ORDER BY date_post,date_mentioned DESC

Answer 1

首先，如果我正确理解您的设计，您需要规范化您的数据库。如我所见，Id_post引用第一个表中的id。但是，您还User_post引用了Id_post的用户，这是不必要的。现在你所描述的不是完全连接，而是第一个表和第一个和第二个表的连接的并集。类似于：

SELECT t.Id_Post, t.Id_User, t.Post, t.Date_post FROM (
    SELECT a.Id_Post, a.Id_User, a.Post, a.Date_post FROM table_posts a
    UNION ALL
    SELECT b.Id_Post, b.Id_User, b.Post, c.Date_mentioned as Date_post 
    FROM table_posts b JOIN table_mentions c ON b.Id_post = c.Id_Post
) t ORDER BY t.Date_post DESC;

Sql加入两个日期排序的两个表

1 个答案: