php 怎样用循环得到一个用户下级及下下级,下下下级...的总人数，下面是我写的一个函数，但结果不正确，谁帮忙看看啊

function subfl($uid,$num1){
    $result1=mysql_query("select * from user where lid='".$uid."'");
    echo "select * from user where lid='".$uid."'";
    $num2=mysql_num_rows($result1)+$num1;
    $num=$num2;

   if($myrow1=mysql_fetch_array($result1)){

  do {
   $this->subfl($myrow1["id"],$num2);
}
  while ($myrow1=mysql_fetch_array($result1));
}else{
  $num1=$num2;