how to find out Current year previous month expression

[AVINASH22]

write an expression to calculate current year previous month sales?

field available:Month(MMMYY formate),year,sales

[sivakumar1994]

sort the chart by year-month and use above (month field) in expression

[rubenmarin]

For use outside dimensions, like in a text box, it can be:
Sum({<Month={'$(=Date(AddMonths(Today(), -1), 'MMMYY'))'}>} sales)