tree database

<?php
/**
 * Created by PhpStorm.
 * User: apelmahmud
 * Date: 02/04/2017
 * Time: 3:24 PM
 */



    $serverName = 'localhost';
    $userName = 'root';
    $pass = '';
    $dbname = 'HR';

    $name ="orko";

    $con = new  mysqli($serverName,$userName,$pass,$dbname);

    if($con->connect_error){

        die("connect fail");
    }

   // $sql = 'select * from employees where employee_id = 3000';




function tree($parent){

    global $con;
    $sql = "select * from employees where manager_id =$parent";
    $result =  $con->query($sql);

    while ($row = $result->fetch_assoc()) {
            echo $row['EMPLOYEE_ID']." ".$row['FIRST_NAME']."<br>";
            tree($row['EMPLOYEE_ID']);

    }

}


    tree(3);






?>