<p>I have a a couple of very simple parameters setup (`cos simple is all I know how to do) which return a start date and an end date.</p>
<p>How can I use the dates entered to return values which are the same dates from the previous year?</p>
<p>So I`d want to be able to enter 01/01/17 and 31/05/17 to get this year`s data but I would also want to see the data from the previous year without entering 2 new dates.</p>
<p> </p>
<p>and invoice.taxdate >= ?<br>
and invoice.taxdate <= ?</p>
