Question

I have a media table and a tag_media table. The tag_media table is a relationship table that contains the columns id_tag and id_media. A single media file can be tagged with multiple tags. Something like:

tag_media:
    id_tag
    id_media

media:
    id_media
    (etc, etc)

I need a query that will allow me to fetch all media that was tagged with a set of mandatory tags and a set of optional tags so that I can guarantee that the returned media were tagged with ALL the mandatory tags and AT LEAST one of the optional tags.

How can I do this?

Answer 1

SELECT m.*
FROM media m
  INNER JOIN (
    SELECT id_media
    FROM tag_media
    GROUP BY id_media
    HAVING COUNT(id_tag IN (required1, required2) OR NULL) = 2
       AND COUNT(id_tag IN (option1, option2, option3) OR NULL) >= 1
  ) t ON m.id_media = t.id_media

This assumes that one media item cannot have duplicate tags.