Dim cBuffer As String = ""
        Dim oDt2 As New DataTable("Aktivitäten")
 
        cBuffer = "SELECT * FROM Aktivitäten, Firma WHERE Aktivitäten.KdNr =" & _
          "Firma.KdNr and Firma.KdNr='" & txtKdNr.Text & "'"
        Dim oCmd2 As New OleDb.OleDbCommand(cBuffer, oConn)
        Dim oDa2 As New OleDb.OleDbDataAdapter(oCmd2)