HOW TO: Enable and Disable DataTable Editing by Using the DataGrid in Visual Basic .NET (320566)

SUMMARY

This step-by-step article demonstrates how to control editing tables in the DataGrid control on a table-by-table basis.

The Navigate event of the DataGrid only fires when you move from DataTable object to DataTable object, not record to record. When you move between DataTable objects, the DataMember property of the DataGrid is set to the relative relationship between DataTable objects. The sample in this article enable and then disables editing for the Details table.

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Requirements

The following list outlines the recommended hardware, software, network infrastructure, and service packs that are required:

• Microsoft Visual Studio .NET
• Microsoft SQL Server 7.0 or Microsoft SQL Server 2000

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Create the Sample to Disable Editing in the Details Table

1. Follow these steps to create a Visual Basic .NET Windows application:
   1. Start Microsoft Visual Studio .NET.
   2. On the File menu, point to New, and then click Project.
   3. In the New Project dialog box, click Visual Basic Projects under Project Types, and then click Windows Application under Templates.
2. Drag a DataGrid control from the toolbox to the form.
3. Add the following code to the top of the form to import the SqlClient namespace:

   Imports System.Data.SqlClient
   					

4. Add the following code to the Form_Load event:

   Dim ds As New DataSet()
   
           Dim stConnect As String = "server=(local);integrated security=sspi;database=northwind"
           Dim cnNorthwind As New SqlConnection(stConnect)
   
           Dim cmCustomers As New SqlCommand("select * from customers", cnNorthwind)
           Dim daCustomers As New SqlDataAdapter(cmCustomers)
           daCustomers.MissingSchemaAction = MissingSchemaAction.AddWithKey
   
           Dim cmOrders As New SqlCommand("select * from orders", cnNorthwind)
           Dim daOrders As New SqlDataAdapter(cmOrders)
           daOrders.MissingSchemaAction = MissingSchemaAction.AddWithKey
   
           Dim cmOrderDetails As New SqlCommand("select * from [order details]", cnNorthwind)
           Dim daOrderDetails As New SqlDataAdapter(cmOrderDetails)
           daOrderDetails.MissingSchemaAction = MissingSchemaAction.AddWithKey
    
           daCustomers.Fill(ds, "Customers")
           daOrders.Fill(ds, "Orders")
           daOrderDetails.Fill(ds, "Details")
   
   'Create the DataRelations between the Customers and Orders DataTables.
   '**********
           Dim dcCustomers_customerID As New DataColumn()
           dcCustomers_customerID = ds.Tables("Customers").Columns("CustomerID")
           Dim dcOrders_CustomerID As New DataColumn()
           dcOrders_CustomerID = ds.Tables("orders").Columns("CustomerID")
   
           Dim drCustomer_To_Orders As New DataRelation("CustomerToOrder", dcCustomers_customerID, dcOrders_CustomerID)
   
           'Add the DataRelation to the Relations collection of the DataSet.
           ds.Relations.Add(drCustomer_To_Orders)
   
   'Create the DataRelation between the Orders and Order details DataTables.
   '**********
           Dim dcOrder_OrderID As New DataColumn()
           dcOrder_OrderID = ds.Tables("Orders").Columns("OrderID")
           Dim dcOrderDetails_OrderID As New DataColumn()
           dcOrderDetails_OrderID = ds.Tables("details").Columns("orderID")
           Dim drOrder_TO_Details As New DataRelation("OrdersTodetails", dcOrder_OrderID, dcOrderDetails_OrderID)
          'Add the DataRelation to the Relations collection of the DataSet.
           ds.Relations.Add(drOrder_TO_Details)
   
           DataGrid1.DataSource = ds.Tables("customers").DefaultView
   					

5. Modify the connection string as appropriate for your environment.
6. Build and run the application.
7. Try to edit any record in the Orders or the Details table. Notice that you can edit the table in the DataGrid even though you set the AllowEdit property of the DefaultView to False.

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Modify the Sample to Disable Editing in the Details Table

1. Stop running the application, double-click the DataGrid, and then add the following code in the DataGrid1_Navigate event:

   If DataGrid1.DataMember <> "" Then
       DataGrid1.ReadOnly = True
   Else
       DataGrid1.ReadOnly = False
   End If
   					

2. Rebuild and run the application.
3. Try to edit any record in the Orders or the Details table. Notice that you have successfully disabled editing in the DataGrid by checking the DataMember property of the DataGrid in its Navigate event and by setting the ReadOnly property of the DataGrid to True.

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Troubleshooting

This sample uses the Northwind database in SQL Server. You can also use this procedure with Microsoft Desktop Engine (MSDE). However, the Northwind database is not included with MSDE. To use this procedure with MSDE, you must import the Northwind database from SQL Server or Microsoft Access. For more information about how to import the Northwind database, see SQL Server Books Online.

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