<script runat="server">
    Sub GridView_SelectedIndexChanged(ByVal sender As Object, ByVal e As _
      EventArgs) Handles GridView.SelectedIndexChanged
 
        ' Retrieve the company name from the appropriate cell.
        Dim companyID As String = GridView.SelectedRow.Cells(1).Text
 
        ' Display company name selected by the user.
        Message.Text = "Sie haben die ID: " & companyID & "ausgewählt."      
    End Sub
</script>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$" & _
  "ConnectionStrings:DBOOEConnectionString %>" 
 
SelectCommand="SELECT * FROM [TB_USER]WHERE [ID]= HIER SOLL DER WERT" & _
  "companyID HIN" UpdateCommand="UPDATE [TB_USER] SET [Vorname] = @Vorname," & _
  "..........