To fetch data from the server at run time by the click of a button, complete the following steps:

1. Double-click button1 (in the sample project, the Create Orders and Fill button at the right of dataGridView2) to bring up the Button1_Click event handler and replace it with the following code:

   To write code in Visual Basic

   Visual Basic	Copy Code
   Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click ordersDataAdapter.Fill(dataSet1) Dim tb As DataTable = dataSet1.Tables("Orders") tb.PrimaryKey = New DataColumn() {tb.Columns("OrderID")} ordersDataGrid.DataSource = dataSet1 ordersDataGrid.DataMember = "Orders" Button1.Enabled = False End Sub

   To write code in C#

   C#	Copy Code
   private void button1_Click(object sender, EventArgs e) { ordersDataAdapter.Fill(dataSet1); DataTable tb = dataSet1.Tables["Orders"]; tb.PrimaryKey = new DataColumn[] { tb.Columns["OrderID"] }; ordersDataGrid.DataSource = dataSet1; ordersDataGrid.DataMember = "Orders"; button1.Enabled = false; }

2. Double-click button2 (in the sample project, the Create OrderDetails and Fill button at the top right of dataGridView3) to bring up the Button2_Click event handler and enter the following code:

   To write code in Visual Basic

   Visual Basic	Copy Code
   Private Sub Button2_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click ordDetDataAdapter.Fill(dataSet1) Dim tb As DataTable = dataSet1.Tables("Order Details") tb.PrimaryKey = New DataColumn() {tb.Columns("OrderID"), tb.Columns("ProductID")} ordDetDataGrid.DataSource = dataSet1.Tables("Order Details") Button2.Enabled = False End Sub

   To write code in C#

   C#	Copy Code
   private void button2_Click(object sender, EventArgs e) { ordDetDataAdapter.Fill(dataSet1); DataTable tb = dataSet1.Tables["Order Details"]; tb.PrimaryKey = new DataColumn[] { tb.Columns["OrderID"], tb.Columns["ProductID"] }; ordDetDataGrid.DataSource = dataSet1.Tables["Order Details"]; button2.Enabled = false; } End Sub

3. Double-click button3 (in the sample project, the Create Relation button at the bottom right of dataGrid3) to bring up the Button3_Click event handler and enter the following code:

   To write code in Visual Basic

   Visual Basic	Copy Code
   Private Sub Button3_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button3.Click Dim rel As New DataRelation("Orders - Order Details", dataSet1.Tables("Orders").Columns("OrderID"), dataSet1.Tables("Order Details").Columns("OrderID")) dataSet1.Relations.Add(rel) Button3.Enabled = False End Sub

   To write code in C#

   C#	Copy Code
   private void button3_Click(object sender, EventArgs e) { DataRelation rel = new DataRelation("Orders - Order Details", dataSet1.Tables["Orders"].Columns["OrderID"], dataSet1.Tables["Order Details"].Columns["OrderID"]); dataSet1.Relations.Add(rel); button3.Enabled = false; }

Run the application and observe the following:

• Notice that the view is inactive (no columns, no rows). This is because the underlying dataSet1 is empty.

  
  
• Press the Create Orders and Fill button, which adds Orders DataTable to dataSet1, filling the view with data.

  This operation is performed by means of the OleDbDataAdapter object (ordersDataAdapter) which operates against Access C1NWind.mdb database. The view is still inactive, because the Order Details DataTable has yet to be added in dataSet1, which is referenced in the view's definition.

  
  
• Press Create OrderDetails and Fill button, notice that the Order Details DataTable has been added to dataSet1 and filled the view with data.
  

  After this, action view is inactive because the join specified in the view's definition supposes presence of DataRelation between joined DataTable(s).

• Finally, press Create Relation button, which creates DataRelation between tables. This operation makes the DataView become active, filling the view with composite rows based on data from underlying DataTable(s).