oh dear-

pardon my ignorance but,
class user{
private $user_id;
private $user_name;
public function __construct($user_id) {
$this -> user_id=$user_id;
$this -> user_name = $result['username'];

what is '$this ->'

>>18
Neither PHP nor Java is an OO language.
EXPERT MIDDLE SCHOOL PROGRAMMING COURSE otherwise. You're part of the problem.