php 로그인시 세션사용

세션담기 :

<?
session_start(); 
$_SESSION['user_id'] = $user_id; 
$_SESSION['user_rno'] = $row[0];
$_SESSION['user_name'] = $row[2];
?>

세션사용 :

<?
session_start(); 
$user_id = $_SESSION['user_id']; 
$user_name = $_SESSION['user_name']; 
$user_div = $_SESSION['user_div']; 
?>