//them mot tai khoan
        public bool addNewAccountModel(AccountModel accountModel)
        {
            bool     result   = false;
            Account  account  = null;
            Cart     cart     = null;
            Customer customer = customerDAO.save <Customer>(accountModel.Customer);

            //kiem tra viec them vao co thanh cong hay khong
            if (customer != null)
            {
                //Them tai khoan
                account = new Account()
                {
                    UserName   = accountModel.UserName,
                    PassWord   = accountModel.PassWord,
                    CustomerId = customer.Id
                };
                account = accountDAO.save <Account>(account);
                //Them gio hang
                cart = new Cart()
                {
                    Code       = DateTime.Now.Ticks.ToString(),
                    CustomerId = customer.Id
                };
                cart = cartDAO.save <Cart>(cart);
            }
            //kiem tra viec them vao co thanh cong hay khong
            if (account != null && cart != null)
            {
                //neu ca 2 them thanh cong
                result = true;
            }
            else
            {
                //neu 1 trong 2 khong them thanh cong
                customerDAO.delete <Customer>(customer);
                if (account != null)
                {
                    accountDAO.delete <Account>(account);
                }
                else if (cart != null)
                {
                    cartDAO.delete <Cart>(cart);
                }
            }
            return(result);
        }