Getting Last Calendar Month

I have a process that searches a db and returns records based on user chosen date filters.  One of the date filters I need is "last calendar month".  For example if the search is done any time in October, the "last calendar month" will return all records from September.

The only thing I have been able to do is to get the rolling total of the last month which, if I search today, would give me all results between Sept 15th, and October 15th, which isn't what we need.

I know there are a lot of date components, and there must be some way to combine them in order to filter records from the last calendar month.

Any tips?

Also, how would I convert a "Date Greater Than" component into a "Date Greater than or Equal To" component?

Thanks.