使用日历表SQL查找去年的会计年度数据

My database has a calendar table that provides the fiscal year, period, etc. based on date (using Teradata with SQLAssistant). I'm trying to get last year's data in a SQL query which I thought would be as simple as adding a -1 in the where clause but it isn't working. I don't want to hard code a date in as I don't want to remember to update the query when the fiscal year changes.My database has a calendar table that provides