session best example

<?php
session_start();

if(!isset($_SESSION['userID']) || (trim($_SESSION['userID']) == '')){
    header('location:index.php');
    exit();
}

$session_id = $_SESSION['userID'];
$session_id = $_SESSION['username'];

?>
$_SESSION :-   userID and username is a DATABASE NAME  as shown in dig



https://www.google.co.in/search?q=session+best+example#q=session+best+example+php 

https://codeforgeek.com/2014/08/session-handling-php/