查询得到论坛线程/回复-只显示最新的一个

Reply_id, thread_id, created, text

查询:

$query = mysqli_query($link, "SELECT * FROM threads, replies 
WHERE threads.thread_id=replies.thread_id AND threads.category_id=$cat 
AND threads.status=1 ORDER BY replies.reply_id DESC");

问题:它只显示具有最新回复的线程。我使用while循环回显所有行。Mysqli_num_rows ($query)显示3，但只打印一个线程。while循环只包含:

while($r = mysqli_fetch_assoc($query))
{
   $thread_id = $r['thread_id'];
                    $total_comments = mysqli_num_rows(mysqli_query($link, "SELECT thread_id FROM replies WHERE thread_id=$thread_id"));
                    $last_comment = mysqli_query($link, "SELECT * FROM replies WHERE thread_id=$thread_id ORDER BY reply_id DESC LIMIT 0,1");
                    $rLastComment = mysqli_fetch_assoc($last_comment);
    $query = mysqli_query($link, "SELECT author FROM threads WHERE thread_id=$thread_id");
    $a = mysqli_fetch_assoc($query);
    echo '<tr>
     <td><img src="" alt=""></td>
     <td><a href="/forum/thread/'.$thread_id.'">'.$status.''.(substr($r['title'], 0, 15)).'</a> </td>
     <td>'.$a['author'].'</td>
     <td>'.($total_comments).'</td>
     <td>'.$lastComment.'</td>
     </tr>';
}