expression for summation of previous 3 months columns for selected month

[#1]

HI Sir,

I am developing Purchase analysis report in that I want to write expression for Consumption qty for last 3 months sum from the selected

month. for that column i have data for 12 months in terms of  columns in a table MVER from SAP database. it includes 12 columns for 12 months how to write the expression for previous 3 months qty from selected month.

Ex : I have selected Aug month then I want summation of qty for May , June , July data from that table columns

[tresesco]

This?

[#3]

HI,

It's working but when I select Jan  then it will gove me GSV00 for latest year instead of that i want GSV12 for previous year. So how I will write expression for that.

[tresesco]

Hope this time, it comes final.