Re: Base Normal Form

David Cressey wrote:
> "Jan Hidders" <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message
> news:Lfeze.139531$Jn.7313539_at_phobos.telenet-ops.be...
>
> > I think that would be very confusing. First, his table actually has
> > ordering, functions don't.
>
> It's not clear to me that a table has ordering, if I understand you
> correctly.

I don't know if "table" has a commonly agreed upon def (and I don't know if it is in the cdt glossary), but I suspect that Jan is right that column ordering would be typical of the common use, if not the definition, of the term. If you use that word without a definition, then there is likely an assumption in the mind of the listener that they can see the table as rows and columns and that if someone else saw this same table, they would see it with the columns in the same order.

Do you have a definition you work with when talking about tables? I tend to refer to them as spreadsheets since the audience can relate to that easily. While spreadsheet columns can be reordered, at any point in time they have an ordering.

> The columns of a table can be referred to by name. While the names can be
> sorted alphabetically, it's not clear that columns have an inherent order.

What is the distinction you make between a table and a relation?

> The rows of a table can be assigned identifying numbers, if desired. Those
> numbers have a natural order, but it's not clear that the rows themselves
> do.
>
>
> That's distinct from the contents of the rows, which can be ordered if the
> domains of the columns are ordered.
>
> And, of course, at some layer of representation, it all has order.

Since we are talking about the definition of a term, I suppose you could define it however you like, but perhaps we could find one or more defs and put them in the glossary since mAsterdam is back.

Cheers! --dawn Received on Fri Jul 08 2005 - 18:25:28 CEST