discuz 高手来！急。。。。

discuz 论坛附件显示，我想去除被删除的用户，被删帖子的，和禁言的用户，的附件不要显示！ sql 要怎么写？高手指教！$query = $db->query("SELECT a.*, p.fid, p.author, t.tid, t.subject, f.name AS fname
FROM {$tablepre}attachments a, {$tablepre}posts p, {$tablepre}threads t, {$tablepre}forums f
WHERE t.tid=a.tid AND f.fid=p.fid AND t.displayorder>='0' AND p.invisible='0' AND a.isimage ='0' AND $sql $orderadd LIMIT $start_limit, $memberperpage");