It seems like you are looking for a system that allows you to declare database constraints of arbitrary complexity. I'm assuming that you want to catch violations of a constraint the moment they are made, and not in some post-factum verification procedure.
To do that, you need a relational DBMS, and alas, such a thing doesn't exist yet.
To do that in an SQL system, your only option is to write a vast lot of constraint enforcement code and stash those in triggers and such. If that is out of the question due to politics and such, there currently is no working solution to your problem.
Beware of those who guide you to Object solutions that cannot be tightly coupled to the DBMS itself. Eventually, someone will deploy some code that bypasses your outside-of-the-dbms constraint enforcement rules, leaving you exactly where you were when you decided to ask this question.
I agree with Spliff. Post factum constraint checking seems like a stupid idea to me too. But if that's what you really want, then here's a possible approach :
According to theory, all database constraints can be formulated as "a query whose result is required to be empty at all times". So such a query would, e.g., give you something like "all the pairs of distinct rows that have the same key value", or, generally speaking, such a query gives you a list of "all the things that are wrong".
Write down queries/scripts at a rate of one per possibly violated constraint, and run those overnight. Test if any of them return non-empty results.