如何列出按常用标签数排序的相关博客文章？

Question

我想显示相关博客帖子的列表，我希望列表按照它们对当前帖子具有的通用标签的数量进行排序。每篇文章可以有多个与之关联的标签。这里是我的表结构：

[文章] < - [帖子到标签接合用表] - > [标签]

我使用PHP和MySQL - 我能做到这一点一个查询？

Answer 1

怎么样...：

SELECT COUNT(*) AS numcommon, posts.pid, posts.post FROM posts 
       INNER JOIN p2t ON p2t.pid = posts.pid 
       WHERE p2t.tid IN 
       (SELECT p2t.tid FROM p2t 
       INNER JOIN posts ON p2t.pid = posts.pid 
       WHERE posts.pid = 1) 
       AND posts.pid != 1 
       GROUP BY posts.pid 
       ORDER BY numcommon 

假设PID作为职位表的主键，TID作为主键标签表，p2t（post to tag）表中的两个外键？

Answer 2

当然，你可以做到在一个查询：

SELECT postid, count(tagid) as common_tag_count 
FROM posts_to_tags 
WHERE tagid IN (SELECT tagid FROM posts_to_tags WHERE postid = 2) 
GROUP BY postid ORDER BY common_tag_count DESC;