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();
}
