[chii]

> Simple, no?

what happens when the business rule clashes with the database's constraint implementation, because different people either misinterpreted, or due to incompetence or miscommunication?

I think splitting up sounds great in theory, but in practise, has lots of pitfalls. That's not to say it's not a good idea, but one musn't look at it with rose-tinted glasses.

[Spearchucker]

Well you'd test, which would catch that scenario. Assuming you're not testing and discover it after releasing to production you'd just use your change process.

Either way this is just part of building a system. Refector, re-test and release (or re-release). It's hardly going to be the only bug you find.