private void btn_order_Click(object sender, EventArgs e)
        {
            string
                bankName = cmbx_bankName.Text,
                duration = cmbx_duration.Text,
                cardType = cmbx_cardType.Text;

            //validation

            CardManager cardManager = new CardManager(bankName, duration, cardType, Session.User);
            Card        card        = cardManager.GetCard();

            //Session.Data.Cards.Add(card);
            using (DatabaseManager db = new DatabaseManager("myDB"))
            {
                db.AddCards(card);
            }

            txbx_number.Text      = card.CardNumber;
            txbx_cvc.Text         = card.CVC.ToString();
            txbx_expiredDate.Text = card.ExpiredDate.ToString();
            MessageBox.Show("Card is done!");
        }