> I remember spending several hours on a bug that was caused by an altered stored procedure. One SQL function was not as it should have been. I don't know if someone had patched it live, or if there had been an unnoticed failure in a DB migration script.

If you have everything under version control you can just reapply that version's stored procedures off the database scripts. If someone or something is not handling failures in deployment scripts (not just database migrations) then you get that sort of problem.