private void countriesTable_CellMouseClick(object sender, DataGridViewCellMouseEventArgs e) { DataTable DT = this.countriesTable.DataSource as DataTable; if (DT != null) { DataRow DR = null; try { DR = ((DataRowView)this.countriesTable.SelectedRows[0].DataBoundItem).Row; } catch (Exception) { return; } if (DR != null) { try { DataRow[] DRS = DR.GetChildRows(this.DS.Relations["CityCountryRelation"]); ((DataTable)this.citiesTable.DataSource).Rows.Clear(); foreach (DataRow r in DRS) { ((DataTable)this.citiesTable.DataSource).Rows.Add(r.ItemArray); } } catch (Exception a) { MessageBox.Show(a.Message); } } } }