>>I've been thinking a lot about date-sensitive datebases. ...
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>I've seen this done before but it's a real pain to code and can lead to some real nightmares in a pure relational model (SQL statements in particular).

Yeah, I've played around with the SQL to deal with this. Using the Max function or Top 1. There doesn't seem to be any simple approach.

I see no reason why this logic could not be built into the SQL language and processed by the data-server. One would simply pass an EFFECTIVE-DATE parameter and everything would happen automatically.


>>A logical extension of these concepts is to store all of the business rules in the database also with effective dates. Then the data can be consistent with the rules at any given point in time.
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>A problem with this is that while it's easy to store parameters for business rules within tables its doggone difficult to store logic. The current mode of thinking with OOP and VFP is to encapsulate business rules in business classes...methods are called in these classes to calculate/validate data. Now, let's compare that to COM (Component Object Model) theory. It states that you can add new interfaces (methods, procedures, whatever) but should never remove them. Kinda fits in with the effective date concept, eh? A simple example that shows both data-driven business parameters and OOP driven business logic...

Thanks for the food for thought!

Peter