Re: Is relational theory irrelevant? (was Re: Dreaming About Redesigning SQL)

"Mikito Harakiri" <mikharakiri_at_yahoo.com> wrote in message news:bdf69bdf.0311091120.14065bc5_at_posting.google.com...
> brennie_at_dcsi.net.au (Bruce) wrote in message
news:<64ea97cf.0311090213.38942cc_at_posting.google.com>...
> > There is an example in this news group from some time ago, where
> > someone used the D4 language (based on Date and Darwen, by Alphora in
> > their Dataphor product) to build a query directly from the user
> > requested query. It was beautiful, <....>
> > The SQL formulation, I believe, would be considerably longer
> > and much obtuse. If I recall correctly, it arose out of an argument
> > over whether SQL was/wasn't truly relational. A one page formaulation
> > including the design of the database.
>
> The reference, please. I find it hard to believe that differences in
> NULL treatment and Multiset Semantics can result in considerable gap
> in expressibility betwen Relational Algebra/D4 and SQL. (What else can
> be the source of D4 superiority?).

Hugh Darwen opinions that dependence on column ordering is SQLs third most severe mistake (after the two you mention). So that's another source of superioity. See here for more:

http://www.hughdarwen.freeola.com/TheThirdManifesto.web/Importance-of-Column-Names.pdf

> SQL had grown to embrace every
> feature in the world, so that I would think that it's easy to make the
> opposite case where 2 line SQL query with analytical extensions would
> be translated into a page of D4 code. It might be that the ANSII
> comittee and vendors didn't really gave much thought to certain SQL
> features, and language orthogonality was certainly not their priority,
> but we can't say that SQL lacks expressibility.

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Mon Nov 17 2003 - 19:43:12 CET