......
$urlindex = 0;
if(empty($arcID))
{
 $row = $dlist->dsql->GetOne("Select id From `#@__cache_feedbackurl` where url='$arcurl' ");
       //此处$arcurl没有过滤
 if(is_array($row)) $urlindex = $row['id'];
      //存在结果则把$urlindex赋值为查询到的$row['id'],我们可以构造SQL语句带入下面的操作中了
}
if(empty($arcID) && empty($urlindex)) exit();
//如果$arcID为空或$urlindex为空则退出
......
if(empty($arcID)) $wq = " urlindex = '$urlindex' "; 
//我们让$arcID为空,刚才上面执行的结果就会被赋值给$wq带入下面的操作中执行了.
else $wq = " aid='$arcID' ";
 $querystring = "select * from `#@__feedback` where $wq and ischeck='1' order by dtime desc";
$dlist->Init();
$dlist->SetSource($querystring);
......