<?php
$data = $database->queryOne("SELECT * FROM users WHERE username=:username and password=:password",array(":username"=>$_POST['loginUsername'],":password"=>$_POST['loginPassword']));
if($data){
    session_start();
    $_SESSION['username']=$data['username'];
    $_SESSION['admin_level']=$data['admin_level'];
    $_SESSION['name']=$data['name'];
    $_SESSION['lastname']=$data['lastname'];
    echo "done";
    header("Location: /");
}
else{
    header("Location: ?error=1");
}