private void btn_in_Click(object sender, EventArgs e) { HoaDonThanhToan m = new HoaDonThanhToan(); m.id_hoadon = int.Parse(txt_MaHoaDon.Text); m.vat = int.Parse(txt_VAT.Text); m.khuyenmai = int.Parse(txt_KhuyenMai.Text); _hoadonbll.CapNhatVatKhuyenMai(m); Frm_PrintfHoaDon hd = new Frm_PrintfHoaDon(int.Parse(txt_MaHoaDon.Text)); hd.Show(); }