public void loadKM() { cbx_SachKM.DataSource = KhuyenMaiBLL.getAllTenSach().DataSource; cbx_SachKM.ValueMember = "ID"; cbx_SachKM.DisplayMember = "TEN"; txt_MaKM.Text = KhuyenMaiBLL.getMaKM().ToString(); dgv_AllKM.DataSource = KhuyenMaiBLL.getAllKM().DataSource; dgv_CTKM.DataSource = null; }