php中的内连接 [英] Inner joins in php

问题描述

SELECT thread.id AS p_id, post.title, post.content, author.username, author.id AS a_id
                         FROM thread INNER JOIN author
                         ON author_id = author.id
                         ORDER BY thread.created DESC
                         LIMIT $start, 30

我有一个名为 posts、posts_id 和 tags 的表.

I have a table called posts, posts_id and tags.

如何使用 INNER JOINS 或其他方式扩展上述 SQL 语句以获取与每个帖子相关的所有标签?

How can I extend the above SQL statement to get all the tags related to each post using INNER JOINS,...or something else?

推荐答案

试试这个(假设带有标签信息的表是标签并且有一个 thread_id 列):

Try this(assumed the table with tag info to be tags and having a thread_id column):

SELECT thread.id AS p_id, 
             post.title, 
             post.content, 
             author.username, 
             author.id AS a_id,
             GROUP_CONCAT(DISTINCT tag_name ORDER BY tag_name DESC SEPARATOR ',') AS tags
 FROM thread INNER JOIN author
 ON author_id = author.id INNER JOING TAGS 
 ON thread.id = tags.thread_id
 GROUP BY thread.id
 ORDER BY thread.created DESC

 LIMIT $start, 30

将 GROUP 向上移动一行.

Moved GROUP By up one line.

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