Re: Base Normal Form

From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Sat, 09 Jul 2005 04:44:57 +0200
Message-ID: <42cf3a29$0$97439$e4fe514c@news.xs4all.nl>

dawn wrote:
> David Cressey wrote:

>>Jan Hidders wrote:
>>>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),

Nope. Except for Jans excellent contribution on NULL and a rephrase of data and meaning in wikipedia nothing much has changed since 0.0.4. If there is more I'll take the time to make a 0.0.5 - or jump to 0.1.0. There was a sub-thread with nice cdt glossary stuff about possreps and unions (by VC and Jon), but nothing copy & pastable enough for the glossary yet :-(

> 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.

Hey! That takes time and care. Oh well.

But I won't stray from the idea that I'll only put into the glossary those terms which triggered misunderstandings. It's not FOLDOC, you know. Received on Fri Jul 08 2005 - 21:44:57 CDT