As DBA's, you can't be the party of "No!". If you have to say "No", which is often, then say "Not exactly, but how about we do it like this instead..." *and* provide sample code. Devs love sample code, it's in a language that they speak fluently.

Most of the friction between the Devs and the DB team at my old place disappeared once both sides got together and agreed upon a set of coding patterns. When both teams have agreed on formal templates for tables, SPs, promotion-to-production scripts, initial lookup table population, and even emergency ad-hoc production updates it's actually funny watching the tribe enforce the policies and seeing the email threads scolding the occasional violators.