How to create pivot table with last 3 months purchase?

[anindya_manna]

Hi,

I want to create a pivot table exactly as below. I have channel name ,Purchase value, month,year in DB. How I can create last 3 months purchase in column value?

[Gysbert_Wassenaar]

Perhaps with an expression like

sum({<month={">=$(=max({<year={`$(=max(year))`}>}month)-2)<=$(=max({<year={`$(=max(year))`}>}month))"}>}[Purchase value])

And perhaps not. It depends on what kind of data values your month field contains. Strings like 'Jul' and 'Aug' won't work in the above expression.