I have the impression that this chapter in the book "QlikView 11 for developers" is pretty complicated.
I have - or rather, an external consultant has - done this in a much easier way, without defining fields to disregard and stuff. In the meantime I've changed it, but here it is:
A set identifier expression for the previous month (based on a selection on a field >month< can come down to the following:
>> Monat = {$(=Month(addmonths(min(Datum_final), -1)))} << - where >Datum_final< is my date field which the month is of course calculated from.
This does not work, however, when you have no selections at all - one would have to nest this inside an IF condition using the Getcurrentselections function to find out whether or not any selection has been done.
