MLM二叉树计数多级

Question

function display_children($parent, $level) {
        $count = 0;
        $result = mysql_query('SELECT user_id FROM sponsers '.'WHERE parent_id="'.$parent.'"');
        while ($row = mysql_fetch_array($result))
        {
               $var = str_repeat(' ',$level).$row['user_id']."
";

                       //echo $var  after remove comment check tree

                       // i call function in while loop until count all user_id 

               $count += 1 +$this->display_children($row['user_id'], $level+1);

        }
        return $count; // it will return all user_id count under parent_id
    } 

Here is my code. I need some help in how will I implement in laravel concept because I'm doing in php concept.

Please help me out. Someone able to share or modified code using laravel 4.2 version