procedure cdsTableBeforePost(DataSet: TDataSet);
var
  z: integer;
  sFieldName: string;
  sOldValue, sNewValue: variant;
begin
  inherited;
  for z := 0 to DataSet.FieldCount - 1 do begin // Interate through all datafields
    if DataSet.Fields[z].OldValue <> DataSEt.Fields[z].NewValue then begin // Only look at fields with changed data
      sFieldName := DataSet.Fields[z].FieldName;
      sOldValue := DataSet.Fields[z].OldValue;
      sNewValue := DataSet.Fields[z].NewValue;
      // ... do something with the retrieved information ...
    end;
  end;
end;