Show one month before current month
I am looking for a simple way to show one month before the current month; this is for an invoice where payment is for the previous month. For example, I want to show today's invoice (created on October 3, 2011) to show the billing period as September, 2011. I can't get the Date functions or Date fields or Data Formatting to make it work. The best solutions would be to get the // to do it in a text field (which I have now creating the current month and year), but a simple field would work, too. Thanks for the help.