如何列出按常用标签数量排序的相关博客帖子？

Question

我想显示相关博客帖子的列表，我希望列表按照当前帖子的常用标签数量排序。每个帖子都可以有多个与之关联的标签。这是我的表结构：

[帖子] <！> lt; - [posts-to-tags-joining-table] - <！> gt; [标签]

我正在使用PHP和MySQL - 我可以在一个查询中执行此操作吗？

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posts表中的主键，tid作为tags表中的主键，p2t（post to tag）表中的两个外键？

Answer 2

当然，您可以在一个查询中执行此操作：

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;