I'd be inclined to say that logic belongs in the application. First, what is the compatibility between databases? I'd never question the likelhood of someone telling you that you can't use SQL Server anymore and have to use Oracle from now on. How difficult would the logic being in the database make that? Second, it's a lot easier to change a database than an application. That sounds like an argument to keep it in the database, but it's not, as I believe that will lead to improperly tested changes.

But I'm no expert.