private void btnThem_MH_Click(object sender, EventArgs e) { flag = "thêm"; BUS_xuly.ClearAllTextBox(groupBox3); txtMaMH.Text = BUS_mh.TaoMaMonHoc(); Enable_MH(); txtTenMh.Focus(); btnSua_MH.Enabled = false; btnCancel_MH.Enabled = false; dgvMonhoc.Enabled = false; }