private void LoadDaTatxtSoGheTrong() { if (cboHangVe.SelectedValue != null) { BUS_TinhTrangVe busTinhTrangVe = new BUS_TinhTrangVe(); txtSoGheTrong.Text = busTinhTrangVe.GetSoGheTrongOfMaChuyenBayAndMaHangVe(cboMaChuyenBay.Text, cboHangVe.SelectedValue.ToString()); } }