Subj : Re: Polymorphism sucks [Was: Paradigms which way to go?]
To   : comp.programming,comp.object
From : Antoon Pardon
Date : Fri Sep 23 2005 09:44 am

Op 2005-09-23, Chris Sonnack schreef <Chris@Sonnack.com>:

> I stand by the original seed: SQL is not a "relational language".
> I also stand by the idea that "relational", in "Relational Database"
> is about *relationships* between records.  I claim that if there are no
> relationships, there's no Relational.

Then IMO you are wrong. It are the records (the tuples) that make
out the relation.


>> The term 'Relation' is instead a different, more precise term for
>> the type of tables used in Relational databases.
>
> Exactly.  Pay attention to the words: "...the TYPE of tables."  Not just
> you plain old tables, but (as quoted above), " table of a cedrtain [sic]
> specific kind".
>
> VERY important distinction.  Here's what I wrote over a month ago:
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Here's a table (first row headers):
>
> NAME      UID      COLOR        DATE          TYPE
> Alice     -        Blue         5-3-1948      BG45
> Bob       -        Red          5-3-1948      XL220
> Carol     3345     Red          12-7-1955     E30F
> Dave      7709     Green        9-14-2000     -
>
> I dispute your "relational==table" definition, so I see not
> one thing that makes this table "relational".  It's just a
> (what I'd call) "flat table".

Then you are wrong. This table is a relation. 

It is a relation between a NAME, UID, COLOR, DATE and TYPE.

Relation is here used in a mathematical sense.

If you consider NAME, UID, COLOR, DATE and TYPE as
sets (of possible values), then a relation is a
subset of NAME * UID * COLOR * DATE * TYPE.

A table as shown above represent such a relation,
because the tuples represent elements from this
product set.

-- 
Antoon Pardon

.