Dim db As Database
Dim rs As Recordset
Dim SQLText As String
Dim a As String
 
If Not IsNull(Me.KombinationsfeldName.Column(2) ) = True Then
 
  a = Me.KombinationsfeldName.Column(2) 
 
  Set db = CurrentDb
  Set rs = Me.RecordsetClone
  rs.FindFirst "feldName = " & a & ""    'hier muß der Feldname deiner Tabelle 
  ' eingetragen werden
 
  If Not rs.NoMatch Then
    Me.Bookmark = rs.Bookmark
  End If
 
End If