如何列出按常用標籤數排序的相關博客文章？

Question

我想顯示相關博客帖子的列表，我希望列表按照它們對當前帖子具有的通用標籤的數量進行排序。每篇文章可以有多個與之關聯的標籤。這裏是我的表結構：

[文章] < - [帖子到標籤接合用表] - > [標籤]

我使用PHP和MySQL - 我能做到這一點一個查詢？

Answer 1

怎麼樣...：

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 

假設PID作爲職位表的主鍵，TID作爲主鍵標籤表，p2t（post to tag）表中的兩個外鍵？

Answer 2

當然，你可以做到在一個查詢：

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;