mysql - 数组中不存在删除值的最佳方法？

Question

我使用这个解决方案，但它使页面加载非常慢注意我使用 MikroTik

$sel_u=mysqli_query($connect,"SELECT * FROM ppp WHERE   serial='".$aa[0]['serial-number']."' ORDER BY id_user ASC")or die(mysqli_error($connect));
  while($fet_u=mysqli_fetch_array($sel_u)){
 $ar=$API->comm('/ppp/secret/print',array(

 "?.id"=>$fet_u['id_user'],
));
 if (count($ar)<mysqli_num_rows($sel_u) AND count($ar)==0){

mysqli_query($connect,"DELETE  FROM ppp WHERE id_user='".$fet_u['id_user']."' AND serial='".$aa[0]['serial-number']."'");

}
}