try {
        // open connection to MongoDB server
        $conn = new MongoClient("mongodb://locidol:locidol@127.0.0.1:27017/quochoi_db");

        // access database
        $db = $conn->quochoi_db;

        // access collection
        $collection = $db->users;


        $username = $_POST['username'];
        $password = $_POST['password'];


        $user = $collection->find(array('user'=> $username, 'pwd'=> $password));

        foreach ($user as $doc) {
    		if (empty($doc)){
			break;
			}
		$_SESSION["username"] = $doc['user'];
		echo "<script>window.location='./manager.php'</script>";
		die();
	}



        // disconnect from server
        $conn->close();

    } catch (MongoConnectionException $e) {
        die('Error connecting to MongoDB server');
    } catch (MongoException $e) {
        die('Error: ' . $e->getMessage());
    }