In order to fill a datagridview according to the selectedvalue of a combobox I've tried creating a stored procedure. However, as I'm not 100% sure what I'm doing, depending on the WHERE statement at the end of my stored procedure, it either returns everything within the table or nothing at all.

This is what's in my class:

Public Function GetAankoopDetails(ByRef DisplayMember As String, ByRef ValueMember As String) As DataTable

    DisplayMember = "AankoopDetailsID"
    ValueMember = "AankoopDetailsID"

    If DS.Tables.Count > 0 Then
        DS.Tables.Remove(DT)
    End If

    DT = DAC.ExecuteDataTable(My.Resources.S_AankoopDetails, _Result, _
                              DAC.Parameter(Const_AankoopID, AankoopID), _
                              DAC.Parameter("@ReturnValue", 0))

    DS.Tables.Add(DT)

    Return DT
End Function

Public Function GetAankoopDetails() As DataTable

    If DS.Tables.Count > 0 Then
        DS.Tables.Remove(DT)
    End If

    DT = DAC.ExecuteDataTable(My.Resources.S_AankoopDetails, _Result, _
                              DAC.Parameter(Const_AankoopID, AankoopID), _
                              DAC.Parameter("@ReturnValue", 0))

    DS.Tables.Add(DT)
    Return DT
End Function

This is the function in the code behind the form I've written in order to fill the datagridview:

  Private Sub GridAankoopDetails_Fill()
    Try
        Me.Cursor = Cursors.WaitCursor
        dgvAankoopDetails.DataSource = Nothing
        _clsAankoopDetails.AankoopDetailsID = cboKeuze.SelectedValue
        dgvAankoopDetails.DataSource = _clsAankoopDetails.GetAankoopDetails



    Catch ex As Exception
        MessageBox.Show("An error occurred while trying to fill the data grid: " & ex.Message, "Oops!", MessageBoxButtons.OK)
    Finally
        Me.Cursor = Cursors.Default
    End Try
End Sub

And finally, this is my stored procedure: (do note that I'm not sure what I'm doing here)

USE [Budget]
GO
/****** Object:  StoredProcedure [dbo].[S_AankoopDetails]    Script Date: 04/12/2010 03:10:52 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[S_AankoopDetails]
(
 @AankoopID int,
 @ReturnValue int output
)
AS
declare @Value int

set @Value =@@rowcount

if @Value = 0
begin
SELECT     dbo.tblAankoopDetails.AankoopDetailsID, dbo.tblAankoopDetails.AankoopID, dbo.tblAankoopDetails.ArtikelID, dbo.tblAankoopDetails.Aantal, 
                      dbo.tblAankoopDetails.Prijs, dbo.tblAankoopDetails.Korting, dbo.tblAankoopDetails.SoortKorting, dbo.tblAankoopDetails.UitgavenDeelGroepID
FROM         dbo.tblAankoopDetails INNER JOIN
                      dbo.tblAankoop ON dbo.tblAankoopDetails.AankoopID = dbo.tblAankoop.AankoopID INNER JOIN
                      dbo.tblArtikel ON dbo.tblAankoopDetails.ArtikelID = dbo.tblArtikel.ArtikelID INNER JOIN
                      dbo.tblUitgavenDeelGroep ON dbo.tblAankoopDetails.UitgavenDeelGroepID = dbo.tblUitgavenDeelGroep.UitgavenDeelGroepID
WHERE dbo.tblAankoopDetails.Deleted = 0 and dbo.tblAankoopDetails.AankoopID = @AankoopID

ORDER BY AankoopID

if @@rowcount >0
   begin
   set @ReturnValue=999
   end
  else
   begin
   set 
   @ReturnValue=997
   end
 end

 if @Value >0
  begin
  --Dit wil zeggen dat ik een gebruiker wil ingeven die reeds bestaat. (998)
  set @ReturnValue=998
 end

Does anyone know what I need to do to resolve this?