Question

我正在开发一个自定义论坛，我注意到我做错了什么。我根据线程日期对线程进行排序。我需要根据线程中最后一篇帖子的日期来组织线程。

我尝试了以下但是它有问题。它多次列出条目。

$thread_sql = "SELECT forum_threads.thread_id AS thread_id,
                      forum_threads.thread_title AS thread_title,
                      forum_threads.thread_description AS thread_description,
                      forum_threads.forum_id AS forum_id,
                      forum_threads.thread_postdate AS thread_date,
                      forum_threads.thread_icon AS thread_icon,
                      forum_threads.thread_views AS thread_views,
                      forum_threads.user_id AS user_id,
                      users.user_firstname AS user_firstname,
                      users.user_lastname AS user_lastname
                 FROM forum_threads
           INNER JOIN users ON forum_threads.user_id = users.user_id
           INNER JOIN forum_posts ON forum_threads.thread_id = forum_posts.thread_id
                WHERE forum_threads.forum_id='$_GET[f]'
             ORDER BY forum_posts.post_date DESC ";

关于如何根据上次回复线程的日期对线程进行排序的任何想法？

Answer 1

首先，我强烈建议将last_post_date添加为forum_thread表的列，每次将帖子添加到线程时都会更新。否则，由于加入，您在论坛中获得更多主题时会出现性能问题。

无论如何，回答你的问题：

$thread_sql = "SELECT forum_threads.thread_id AS thread_id,
                  forum_threads.thread_title AS thread_title,
                  forum_threads.thread_description AS thread_description,
                  forum_threads.forum_id AS forum_id,
                  forum_threads.thread_postdate AS thread_date,
                  forum_threads.thread_icon AS thread_icon,
                  forum_threads.thread_views AS thread_views,
                  forum_threads.user_id AS user_id,
                  users.user_firstname AS user_firstname,
                  users.user_lastname AS user_lastname, 
                  max(forum_posts.post_date) last_post_date
             FROM forum_threads
       INNER JOIN users ON forum_threads.user_id = users.user_id
       INNER JOIN forum_posts ON forum_threads.thread_id = forum_posts.thread_id
            WHERE forum_threads.forum_id='$_GET[f]'
            group by 
                  forum_threads.thread_id,
                  forum_threads.thread_title,
                  forum_threads.thread_description,
                  forum_threads.forum_id,
                  forum_threads.thread_postdate,
                  forum_threads.thread_icon,
                  forum_threads.thread_views,
                  forum_threads.user_id,
                  users.user_firstname,
                  users.user_lastname 
         ORDER BY max(forum_posts.post_date) DESC ";

此外，我认为这样的事情可能会更快：

SELECT forum_threads.thread_id AS thread_id,
       forum_threads.thread_title AS thread_title,
       forum_threads.thread_description AS thread_description,
       forum_threads.forum_id AS forum_id,
       forum_threads.thread_postdate AS thread_date,
       forum_threads.thread_icon AS thread_icon,
       forum_threads.thread_views AS thread_views,
       forum_threads.user_id AS user_id,
       users.user_firstname AS user_firstname,
       users.user_lastname AS user_lastname
      (SELECT MAX(post_date) 
       FROM forum_posts
       WHERE thread_id = forum_threads.thread_id) last_post_date
   FROM forum_threads
   INNER JOIN users ON forum_threads.user_id = users.user_id
   WHERE forum_threads.forum_id='$_GET[f]'
   ORDER BY last_post_date DESC;

按最后发布日期排序论坛

1 个答案: