I have a DB where I want to compare 2 set of dates. For example how many items were sold this year for a specific 28 day, monthly and yearly period vs the same last year. I can run the query 3 times, once for each of the specific date ranges, but I want to be able to compare those dates ranges. i.e 1/1/2016 to 1/29/16 vs 1/1/15 to 1/1/15.