Question

我需要从3个表中检索数据：t_users，t_forum，t_replies。帖子，海报和该帖子的回复数量。

我已经让它像这样工作，但我看不到一个选项，可以通过大多数回复对它进行排序。

$_result= $_PDO->query("
   SELECT * FROM t_users, t_forum 
   WHERE t_forum.d_op= t_users.d_user_id
   $_orderBy");

    if ($_result->rowCount() > 0) {

    while($_row = $_result-> fetch(PDO::FETCH_ASSOC)){

    $_postid = $_row['d_index'];

      //count amount of replies per post
      $_replycount = $_PDO ->query("SELECT COUNT(*) 
                                    FROM t_replies 
                                    WHERE d_reply_id = '$_postid'");

     $_count = $_replycount ->fetchColumn();
     }
     }

    //I have tried queries like this :
       SELECT  t_users.*, t_forum.*, COUNT(d_reply_id)
       FROM t_users,t_forum, t_replies
       WHERE t_forum.d_op= t_users.d_user_id
       AND t_forum.d_index = t_replies.d_reply_id

    //but this only retrieves one row and literally counts the d_reply_id value as the
   value is numeric, thank you for reading.

Answer 1

您的查询应如下所示：

SELECT  /*put here field of thread and poster*/, COUNT(d_reply_id)
FROM t_users

join t_forum 
on t_forum.d_op= t_users.d_user_id

left join t_replies
on t_forum.d_index = t_replies.d_reply_id

group by /*put here field of thread and poster*/
order by COUNT(d_reply_id) desc

需要按其他表SQL中的回复数量对结果进行排序

1 个答案: