Re: How can I create/relate historical data in qlik sense?
What i understood from your requirement is that you need to have data for the last 4 months including the current months. So in march you need data from dec-jan-feb-march. If this is what you want a simple where clause will do.
Where your_date_field >= monthstart(addmonths(today(),-3)) and your_date_field <= monthend(today());