MySql 连接 3 个表 - 多重连接

Question

SELECT type_files.html_embed_before
   , script_files.path
   , type_files.html_embed_after
FROM type_files
INNER JOIN script_files ON (type_files.type = script_files.type)

上面的代码为我提供了所有 script_files 的信息。 我想在查询的基础上得到

• script_files.id = script_match.file_id

• script_matches.ap_id 等于 article.head、header.head 或 footer.head。

• 将传入文章、页眉、页脚的ID

Answer 1

我最不了解的要求是您从 script_match 到文章、页眉和页脚的链接。如果我理解正确，这应该是你想要的。

SELECT tf.html_embed_before
   , sf.path
   , tf.html_embed_after
FROM type_files AS tf
INNER JOIN script_files AS sf ON tf.type = sf.type
INNER JOIN script_match AS sm ON sf.Id = sm.file_id
WHERE sm.ap_id IN
(
   SELECT a.head
   FROM article AS a
   WHERE a.id = @yourId

   UNION ALL

   SELECT h.head
   FROM header AS h
   WHERE h.id = @yourId

   UNION ALL

   SELECT f.head
   FROM footer AS f
   WHERE f.id = @yourId
)

MySQL JOIN 文档

Jeff Atwood's Coding Horror article on Joins