login with pdo php

?php include("config.php"); session_start(); $user_check=$_SESSION['login_user']; $admin = $db-prepare('SELECT * FROM admin WHERE username = :username'); $admin-execute(array( ':username' = $user_check )); $row = $admin-fetch(PDO::FETCH_ASSOC); $login_session=$row['username']; if(!isset($login_session)) { header("Location: login.php"); } ? dragon99bet login