mysql多对多关系查询。如何获取已过滤帖子的所有标签？

好吧，这是我在凌晨4:30想到的最好的方法：

SELECt distinct tag_id FROM    (SELECt pt1.post_id FROM pt1    INNER JOIN tags t1 ON (pt1.tag_id = t1.id)    WHERe t1.id IN (1, 2)    GROUP BY pt1.post_id    HAVINg COUNT(DISTINCT t1.id) = 2) MatchingPostsINNER JOIN pt2 ON (MatchingPosts.post_id = pt2.post_id)WHERe (pt2.tag_id NOT IN (1, 2))

（1，2）是您要寻找的标签，计数当然必须与您要用来过滤的标签数量相匹配。