You will need two date parameters only:
{@Report From} and {@Report To}.

By using these two parameters, you can then create another two formulas  to get the last year period.

{@Same Period Last Yr From}
DateAdd("yyyy", -1, {@Report From})

{@Same Period Last Yr To}
DateAdd("yyyy", -1, {@Report To})

Then, to get the last year sales, another formula
{@Sales last year}
If sales.date in {@Same Period Last Yr From} to {@Same Period Last Yr To}
then sales.sales
else 0

To get current year sales
{@Sales this year}
If sales.date in {@Report From} to {@Report To}
Then sales.sales
else 0

Hope this helps!


Edited by lolly54 - 25 Mar 2014 at 11:19pm