public static bool ThoiHoc(List <string> listMaTre, string maLop) { foreach (string maTre in listMaTre) { if (string.Compare(TreDAL.GetTinhTrangTrongLop(maTre, maLop).Trim(), "0") == 0) { try { TreDAL.ThoiHoc(maTre, maLop); } catch (Exception ex) { MessageBox.Show(ex.Message); } } else { return(false); } } return(true); }