How to use a ButtonColumn in a DataGrid

<asp:DataGrid id='DataGrid1' OnItemCommand ='ItemCmd' AutoGenerateColumns =False  runat='server'>
	<Columns>
		<asp:BoundColumn DataField='ProductID' HeaderText='ProductID'></asp:BoundColumn>
		<asp:BoundColumn DataField='Productname' HeaderText='Productname'></asp:BoundColumn>
		<asp:ButtonColumn DataTextField='Productid' CommandName='Show' HeaderText='Productid' ButtonType='PushButton'
			Text='Click'></asp:ButtonColumn>
	</Columns>
</asp:DataGrid>

VB.NET

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
	’Put user code to initialize the page here
	If Not Page.IsPostBack Then
	            ’Populate the DataGrid
	End If
End Sub

Protected Sub ItemCmd(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) 
	If e.CommandName = 'Show' Then
	            Response.Write(e.Item.Cells(1).Text)
	End If
End Sub

C#

private void Page_Load(object sender, System.EventArgs e)
{
	// Put user code to initialize the page here
	if (!Page.IsPostBack )
	{
		//Populate the DataGrid
	}
}

protected void ItemCmd(Object source   , System.Web.UI.WebControls.DataGridCommandEventArgs e   ) 
{ 
	if (e.CommandName.ToString () == 'Show')
	{
		Response.Write(e.Item.Cells[1].Text);
	}
}