Is there any way to compare values through a portal?

I have a people database pulling each individuals donations through a portal and want to be able to evaluate whether their most recent donation went up or down from the previous donation.

Ideas?

You need to do this in the Donations table. A relationship from Donations to anther TO of Donations, let's call it PreviousDonations, based on:

Donations::DonorID = PreviousDonations::DonorID

AND

Donations::Date > PreviousDonations::Date

will show all previous donations of the same donor. This relationship needs to be sorted by date, descending.

Now you can have a calculation field in Donations, for example:

Case (

not IsEmpty ( PrevDonations::DonationID ) ;

Choose ( 1 + Sign ( Sum - PrevDonations::Sum ) ; "LESS" ; "SAME" ; "MORE" )

)

This field would go into the portal. You could even calculate the change in %, etc.