I have to write an app (Using SF) which right now will link into VFP databases but in a year or so these VFP databases will be upgraded to SQL Server.

I realise I will have to do some changes but want to keep them to a minimum and am planning now . One of the things I've run into with the OleDB driver is if I am  updating or inserting, in VFP , named parameters cannot be used and you end up with about 40 question marks. (All my Apps so far in SF have been with Sql Server so here I am referring to writing an APP not using SF)

I'm looking for pointers in the design, so that when I come to use the APP with SQL Server, my mods will be down to a minimum. I also don't want to necessarily build a whole factory with options for VFP and SQL, i.e. I am happy enough to make hard coded changes as long as they are kept to a minimum