private void buttonSua_Click(object sender, EventArgs e) { monhocbus.SuaMonHoc(textBoxMaMon.Text, textBoxTenMon.Text, comboMaKhoa.SelectedItem.ToString()); dataGridViewDS_MH.DataSource = monhocbus.XemTatCaMonHoc(); textBoxTongSo.Text = (dataGridViewDS_MH.RowCount).ToString(); }