Had to get creative, but this should work to get the purchase date, if and only if:
- The warranty date is already populated
- The warranty date minus x is the true purchase date
- x = number of years the warranty is good for
DateAdd(YEAR, -x, tblAssetCustom.Warrantydate) As [Purchase Date]
And to put it in a year format, you can do this:
Cast(DateDiff(dd, (DateAdd(YEAR, -x, tblAssetCustom.Warrantydate)),
GetDate()) / 365.2425 As numeric(8,1)) As [Age (Years)]
Hopefully this helps someone.
Edit: Edited for clarity.