public frmDSHoaDon(string maKH) { InitializeComponent(); dgvDSHoaDon.DataSource = hoadonBLL.GetHDFromKhachHang(maKH); if (dgvDSHoaDon.Rows.Count > 0) { hoaDon = hoadonBLL.GetHoaDonByID(dgvDSHoaDon.Rows[0].Cells[0].Value.ToString()); ShowInfoHoaDon(hoaDon); } }