Public Enum ltDomWert
     ltDLookup = 0
     ltDCount = 1
     ltDMax = 2
     ltDMin = 3
     ltDFirst = 4
     ltDLast = 5
     ltDSum = 6
     ltDAvg = 7
 End Enum
 
 Function fcDomWert(Expression As String, Domain As String, _
     Optional Criteria As String, _
     Optional ltDomArt As ltDomWert) As Variant
     Dim bytWert As Byte
     Dim strSQL As String
     Dim rs As DAO.Recordset
     If IsMissing(ltDomArt) Then
         bytWert = 0
     Else
         bytWert = ltDomArt
     End If
     Select Case bytWert
         Case 0: strSQL$ = "SELECT " & Expression$ & " FROM " & Domain$
         Case 1: strSQL$ = "SELECT COUNT(" & Expression$ & ") FROM " & Domain$
         Case 2: strSQL$ = "SELECT MAX(" & Expression$ & ") FROM " & Domain$
         Case 3: strSQL$ = "SELECT SUM(" & Expression$ & ") FROM " & Domain$
         Case 4: strSQL$ = "SELECT FIRST(" & Expression$ & ") FROM " & Domain$
         Case 5: strSQL$ = "SELECT LAST(" & Expression$ & ") FROM " & Domain$
         Case 6: strSQL$ = "SELECT SUM(" & Expression$ & ") FROM " & Domain$
         Case 7: strSQL$ = "SELECT AVG(" & Expression$ & ") FROM " & Domain$
     End Select
     If Nz(Criteria$, "") <> "" Then strSQL$ = strSQL$ & " WHERE " & Criteria$
     Set rs = CurrentDb.OpenRecordset(strSQL$, dbOpenForwardOnly)
     If rs.EOF Then
         fcDomWert = Null
     Else
         fcDomWert = rs.Fields(0)
     End If
     rs.Close
     Set rs = Nothing
 End Function

Dim i As Integer
 i = fcDomWert("DeinAutowertfeld", "DeineTabelle", "[DeinKriteriumsfeld] = " _
     & DeinKriterium, ltDCount)