Question

这些是表格：

threads:
id, date, title, text


comments:
id, thread_id, date, comment

我该如何列出最后一个评论的帖子？

目前看起来如此：

$threads = mysql_query("SELECT id, title FROM threads ORDER BY date ASC");

while ($thread = mysql_fetch_assoc($threads)) {

 echo $thread['title'];

}

我无法想象这个人。所以，如果有人能给我一个很棒的手！

干杯！

Answer 1

试试这个：

SELECT DISTINCT t.id, t.title
  FROM threads t LEFT JOIN comments c ON t.id = c.thread_id
 ORDER BY c.date DESC

如果线程没有注释，则需要左连接。

Answer 2

这个应该完成它：

SELECT threads.id, threads.title, max(comments.date)
   FROM threads 
    LEFT OUTER JOIN comments
   ON threads.id = comments.thread_id
GROUP BY threads.id, threads.title
ORDER BY max(comments.date) DESC

Answer 3

select * from Threads t
    inner join Comments c
        on t.id = c.Thread_id
order by c.date

Answer 4

由于您需要一个包含最新评论的主题列表，您必须按ID加入，然后按评论日期对DESC进行排序。

SELECT t.id, t.title, c.date
FROM threads t, comments c
WHERE t.id = c.thread_id
ORDER BY c.date DESC

由于

我应该如何加入这些表？

4 个答案: