Re: MV Keys

In article <1141261284.404545.215620_at_v46g2000cwv.googlegroups.com>, marshall.spight_at_gmail.com says...
> dawn wrote:
> > Although all NF's are defined as first requiring 1NF, at least with
> > Codd and his camps.
>
> Indirectly, insofar as for all N, normal form N subsumes the definition
> of normal form N-1. Again, is there any reason we should care?

Yes. This means that we can check to see if a relvar is in 5NF, and not need to check the lesser ones.

> > I agree with Date tossing out normalization as defined by Codd, but not
> > with his attempt to redefine 1NF to be meaningless. It is difficult to
> > move foward if people still have the mistaken impression that database
> > theory requires that we remove repeating groups.
>
> Repeating groups are still a bad idea, regardless of whether we
> allow nested relations or not. I don't agree that allowing
> nested relations means we're going to want to start using
> repeating groups.

How do you define "repeating group" as opposed to "nested relation", then? I assume "nested relation" and "relation-valued attribute" is the same thing.

-- 
Jon