Re: MV Keys

In article <1141325959.909042.77180_at_j33g2000cwa.googlegroups.com>, marshall.spight_at_gmail.com says...
> Jon Heggland wrote:
> >
> > How do you define "repeating group" as opposed to "nested relation",
> > then?
>
> A repeating group is a set of attributes, all doing the same thing,
> but repeated to allow higher cardinality. Nested relation/RVA
> is a single atribute whose type is relation. An example of a
> repeating group is allowing up to three phone numbers for a
> customer by having three attributes, PhoneNumber1,
> PhoneNumber2, and PhoneNumber3. This approach has
> significant disadvantages.

As in the 1NF definition I numbered #2, then?

Do you consider this kind of repeating groups to break 1NF?

> (I was under the impression this usage was quite standardized;
> yes? No?)

Not in my experience, no. It is regrettable that we have to go to all this trouble to be explicit and precise; it is a sign of the weakness of the traditional 1NF concept, I think.

-- 
Jon