Considering how many textures I have in my inventory and how many textures some of the more senior members have in their inventories--some of them likely hundreds of megabytes in total storage space--I can't imagine how, say, a 10MB database limit for database access in script is going to bring down the servers.
And I'm not sure about full-blown SQL but if not then I think something could be invented that comes very close, maybe some lighter wrapper like ADO or JDO style interface. It's not much trouble to write up a stored procedure that allocates a 10MB database for a user once they upgrade for a Premium membership, and heck, Linden is already pushing its servers with the strange jobbers you people are doing in script in order to make up for this lack.