[slap_shot]

This is exactly the issue here. I worked as a contractor for the State Department for a couple of years on software that basically held the record of every dollar spent over the last 20 years.

What seemed like a very small and simple problem initially revealed itself to be massive problem that even a team of 35 struggled to maintain. The purchase history for any given item spanned multiple systems with completely different topologies of data glued together by, literally, tens of thousands of lines of SQL.

The project had been around for ~17 years when I worked on it and while data was landed in a final format where a query like the above could have been done, I wouldn't bet any serious money that the calculations were correct.

Some five or six multi-million dollar rewrites had been attempted, but could never be done.

Not to say Ohio's system is that this level, but I doubt there's a giant table sitting somewhere that such a simple query could be applied to.

I like to think that somewhere in all that SQL was an Office Space-esque line of SQL syphoning off a few cents per transaction, but was never able to find one :)