Re: Terminology for composite attributes

dawn wrote:
> I was a bit concerned that the map from reality to conceptual model
> might prompt responses such as this. I'd like to discuss your point
> too, but my question is really about terms that would work for
> describing the move from a scalar value to a struct (multiple scalar
> values of possibly different types), given a particular logical
model.
>

I still think David Cressey's message provides a pretty good explanation. And I also think that the term "composite attributes" is confusing.
>

> So, replace "Person" with "A" and "Phone" with "B" and so on so that
> the reality mapping doesn't interfere. Using a relational model,
both
> multivalued attributes and composite attributes

It is unclear how you arrived here. Can you, in more detail, tell us how you arrived at these relations - with "composite attributes" - before splitting them out.

get split out into
> separate relations before the logical modeling is completed, but
before
> that happens there is a recognition by the modeler that what was a
> single value must now hold multivalues (in the one case) or what was
a
> single value must now hold a "composite value."
>
> Does that terminology work or is there a better way to say it?
>
> Then we can chat about your point and the mapping from reality that
> might put HairColor as an attribute of Person even though it is
clearly
> an attribute of Hair.

As far as I know, in Biology the hair color of a person is determined by his or her DNA. And DNA is a "person-level". I am also confused by why you decided to compare David's Person-Phone relationship to Person-Haircolor; there is a big difference between the two.

>
> smiles. --dawn
> P.S. I'll have to figure out how google groups posting lets me
include
> a quote from post I'm replying to, but will send this without for
now.

Vladimir Odrljin Received on Wed Mar 23 2005 - 23:34:28 CET