private void GetOrdersButton_Click(object sender, EventArgs e) 
{ 
// Get the CustomerID for the row selected in the CustomersGrid 
string selectedCustomerID = 
(string)CustomersGrid.SelectedCells[0].OwningRow.Cells["CustomerID"].Value; 

// Create a DataRowView and assign it the selected row. 
DataRowView selectedRow = customersDataView[customersDataView.Find(selectedCustomerID)]; 

// Call the CreateChildView method to 
// navigate the relationship and create a 
// new DataView based on the related records. 
ordersDataView = selectedRow.CreateChildView 
(northwindDataSet1.Relations["FK_Orders_Customers"]); 

// Set the OrdersGrid to display the related Dataview 
OrdersGrid.DataSource = ordersDataView;