SQL查詢以查找具有至少一個列出標簽的文章

Question

我有3個表：articles，tags和article_tag（連接它們的表）。

我想查找所有在查詢中列出一些（或全部）標簽的文章，並按匹配標簽的數量對其進行排序。 可能嗎？

用英語舉例：

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

大概是這樣的：

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

Answer 2

select a.* from articles a,
 (select article_id, count(*) cnt from article_tag at, tag t
  where t.name in ('jazz', 'bass-guitar', 'soul', 'funk')
  and at.tag_id = t.tag_id
  group by article_id) art_tag
where a.article_id = art_tag.article_id
order by art_tag.cnt desc