Subj : Re: Polymorphism sucks [Was: Paradigms which way to go?]
To   : comp.programming,comp.object
From : topmind
Date : Fri Sep 23 2005 08:14 pm


Chris Sonnack wrote:
> Christian Brunschen writes:
>
> >>> At this point, the reader may be wondering why relational databases are
> >>> called "relational" anyway. The answer is simple: "Relation" is just a
> >>> mathematical term for a table (to be precise, a table of a cedrtain
> >>> specific kind - details to follow in Chapter 11).
> >>
> >> Ah ha.  A certain specific KIND of table.  Okay, let's skip to Ch.11....
> >
> > Yes, a specific kind of table.
>
> Okay, let me just start by saying, "Okay, I see that a 'relation' is indeed
> a (specific kind of) 'table', and we can consider the issue closed."
>
> The rest of this is just in nitpicky programmer Friday afternoon fun....
>
> I'm not entirely sure I agree (at this point) that a 'relational database'
> does not consist of relations that are, in fact, um, related.  It seems
> that a single relation with no relationSHIPS isn't very useful, nor is it
> much of a database.
>

One could still do useful queries such as "show me all green products
with a list price of less than 5.00" on a single table/view. In fact,
often the goal is to produce a single table "view" from joined tables
with all the columns needed to do simple predicate queries. In other
words, one often spends the first half of the query effort producing
the proper single-table view via joins, and then the 2nd half use those
(some calculated) columns as if they were part of only one actual
table.

-T-

.