public void AddQuantity(string tendangnhap, string idsizesanpham, int quantity)
{
if (tendangnhap != null && tendangnhap != "")
{
TaiKhoanBUS taikhoanbus = new TaiKhoanBUS();
TaiKhoan taikhoan = taikhoanbus.CheckTaiKhoan(tendangnhap);
GioHangBUS giohangbus = new GioHangBUS();
giohangbus.AddQuantity(taikhoan.Id.ToString(), idsizesanpham, quantity);
}
}