Question

I have 3 tables: articles, tags and article_tag (the one which connects them).

I’d like to find all articles that have some (or all) of the tags listed in the query and order them by the number of matched tags. Is it possible?

Example in english:

Query: Find me all articles that have at least one of these tags "jazz, bass guitar, soul, funk", order them by the number of matched tags.

Output:
Article 1 (jazz, bass-guitar, soul, funk)
Article 2 (jazz, bass-guitar, soul)
Article 3 (jazz, bass-guitar)
Article 4 (funk)

Answer 1

Probably something like this:

select articles.article_id, count(tags.tag_id) as num_tags, group_concat(distinct tag_name separator ',') as tags
from articles, article_tag, tags
where articles.tag_id = article_tag.tag_id
  and article_tag.tag_id = tags.tag_id
  and tags.tag_name in ( 'jazz', 'funk', 'soul', 'Britney Spears' )
group by articles.article_id
order by count(tags.tag_id) desc