Re: Database schema for univesal usage

mountain man wrote:
>
> It was a brief discussion only for the purpose of asking the
> following two questions which have not yet been answered:
>
> 1) Is it clear/true that Date's "abstract machine" necessarily
> evolves due to change management considerations over
> time? (eg: expansion of business to include widgets)

Yes, this is usually known as "schema evolution" and used to be a popular research subject in the database and data modelling communities.

> 2) Does Date reference this issue?

A little. He usually discusses some of the research that has been going on in that area. Unfortunately, and that is certainly not Date's fault, there is still not a nice single broad theory on how that problem should be approached, but rather a lot of ad-hoc approaches and a few partial theoretical results here and there.

• Jan Hidders