Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) _
  Handles Me.Load
 
        Dim vDat As String
        Dim bDat As String
 
        Select Case cbxAuswahl.SelectedIndex
 
            Case 0 ' Januar
                vDat = "#01/01/2010"
                bDat = "#01/31/2010"
 
            Case 1 ' Februar
                vDat = "#02/01/2010#"
                bDat = "#02/28/2010#"
 
            case .... 
 
        End Select
 
        TextBox1.Text = vDat
        TextBox2.Text = bDat
 
        '//Datenbankquelle, und Datensätze aus Datenbank selectieren
        With AccessDataSource1
            .DataFile = "mydatabase2.mdb"
            .SelectCommand = "SELECT * FROM MyTable WHERE (MyTable.Datum >=" _
              & vDat & ") AND (MyTable.Datum <=" & bDat & ")"
        End With

<asp:GridView ID="GridView1" runat="server" DataSourceID="AccessDataSource1" 
   AutoGenerateColumns="False" HorizontalAlign="Center" GridLines="None" 
   AllowPaging="True">
     <PagerSettings (...)/>
     <Columns>
       <asp:BoundField DataField="Feld1" 
          SortExpression="Feld1">
       </asp:BoundField>
 
       <asp:BoundField DataField="Feld2"</asp:BoundField>
     </Columns>
</asp:GridView>