private void btnChon_Click(object sender, EventArgs e) { bool Chon = false; try { foreach (DataRow dr in dtLop.Rows) { if (bool.Parse(dr["Chon"].ToString()) == true) { Chon = true; pKQHT_CTDT_LopInfo.IDDM_Lop = int.Parse(dr["DM_LopID"].ToString()); oBKQHT_CTDT_Lop.Add(pKQHT_CTDT_LopInfo); } } if (Chon == false) { ThongBao("Bạn chưa chọn lớp nào."); } else { this.Tag = "1"; this.Close(); } } catch (Exception ex) { ThongBao(ex.Message); } }