Hi,
I have very limited knowledge about oracle functions but you can follow below steps.
Create Month Year Object in the universe based on the date you want to filter the data in webi report.
Create Previous Month object in the universe.
Ignore my object table column mapping. You need to create the object based on the system date.
Like
to_char(add_months(sysdate,-1),'MM-YYYY')
It will not parse but it will work in report.Keep the data data type as character.
Create Previous Month-2 object in the universe based on the sysdate.
to_char(add_months(sysdate,-2),'MM-YYYY')
It will not parse but it will work in report.Keep the data data type as character.
create webi report and add filter like this to get the last two months data.
see the result.If you schedule the report every time you will get the last two month data in webi.
Amit