Re: Units of Measurement in the Database Model

"David J. Aronson" wrote in message news:3CBCBCE2.CD7B395C_at_att.net...
> Daniel Dudley wrote:
> >
> > "David J. Aronson" wrote
> ...
> > > If, as I thought, you were thinking of the "foreign key into
> > > UoM registry" case, then I agree with all that you said.
> ...
> > Right on, although I do dislike the use of the term
> > "foreign key" when discussing lookup tables.
>
> Why? What is your preferred term for such a case?

How about "lookup value"? ;-)

A lookup table need not have indexes; indeed, they often don't (for reasons given in my previous messages). In short, the cost of maintaining an index on a lookup table is usually too high to justify its use.

> When do you prefer to use the term "foreign key"?

A key (foreign or otherwise) is synonymous with the use of an index. Key values are (or should be) simple IDs which are stored in an index to facilitate fast access to and ordering of the actual (structured) data.

> (BTW, I'm coming at this
> thread from the c.s-e angle, and I ass-u-me you're from c.d or
> c.d.t, so this would be a good chance for me to get another
> perspective on it.)

You assume correctly, I don't subscribe to c.s-e.

[...]

Daniel Received on Wed Apr 17 2002 - 22:57:19 CEST