Date Operations

[eluser]Unknown[/eluser]
I Have a Oracle database, with a DATE field (date_xpto).
i need to make operations with that field, like this (sorry for the kind of pseudo code):

if ( (now() - date_xpto ) > 5 days) echo "Expired";

how can i do this? is there a standard way to make operations with dates?

[eluser]vitoco[/eluser]
you wanna do this in a store procedure or in php with the result of a query to the db ?