Incomplete understanding of input or domain is certainly a cause of problems, and I don't know that there is a way the type system can help in the general case.
With regard to databases in particular, though, it is comparatively easy to constrain things so that you don't have that problem, and enlisting the type system there makes sense. There are other areas that have useful approaches as well - consider protocol buffers, for instance.
I prefer to let the type system catch what it can, and use tests for where it can't - often type info can be leveraged to help in the testing, too: I recommend checking out quickcheck if you haven't.
With regard to databases in particular, though, it is comparatively easy to constrain things so that you don't have that problem, and enlisting the type system there makes sense. There are other areas that have useful approaches as well - consider protocol buffers, for instance.
I prefer to let the type system catch what it can, and use tests for where it can't - often type info can be leveraged to help in the testing, too: I recommend checking out quickcheck if you haven't.