@Gail, I think you have the right classification there. If anything, the cause was a "type mismatch". You can't really say that "IVAN YEARS" was invalid, only that it was...

On a less flippant note, Chris Date (among others) has argued that database systems should explicitly prohibit anything which is not allowed. That increases work in the short term, but...

Gail, I don't know if I would call this example of dirty data "weird" or "worrying" but it was certainly odd. We called it "The Curse of IVAN YEARS".

In...

I'm new here but Gary's editorial caught my attention. I think this discussion is really useful.

Gary has identified "Development" and "Administration". My suggestion is that you want another category...