Re: Is mysql a RDBMS ?
Date: Mon, 25 Aug 2003 06:16:07 GMT
Message-ID: <HQh2b.2331$Jh2.1999_at_newsread4.news.pas.earthlink.net>
"Bob Badour" <bbadour_at_golden.net> wrote in message
news:YBh2b.643$9I6.77372456_at_mantis.golden.net...
> "Daniel Guntermann" <guntermann_at_earthlink.net> wrote in message
> news:Gmg2b.2278$Jh2.287_at_newsread4.news.pas.earthlink.net...
> >
> > "Bob Badour" <bbadour_at_golden.net> wrote in message
> > news:Vj52b.593$q25.72766566_at_mantis.golden.net...
> > > "Heikki Tuuri" <Heikki.Tuuri_at_innodb.com> wrote in message
> > > news:0d12b.203$yu.178_at_read3.inet.fi...
> > > > Morten,
> > > >
> > > > "Morten Gulbrandsen" <Morten.Gulbrandsen_at_rwth-aachen.de> kirjoitti
> > > viestiss?
> > > > news:60ca69db.0308210016.822e230_at_posting.google.com...
> > > > > Hello,
> >
> > [...]
> >
> > > > >
> > > > > From Elmasri:
> > > > >
> > > > > To qualify as a genuine relational DBMS,
> > > > > a system must have at least the following properties:
> > > > >
> > > > > 1.) It must store data as relations such that each column is
> > > > > independently identified by its column name and the ordering of
rows
> > > > > is immaterial.
> > > >
> > > > This holds for MySQL.
> > >
> > > Are you saying that the following works with MySQL?
> > >
> > > select somecharfield name, someintfield id
> > > from sometable
> > > union
> > > select anotherintfield id, anothercharfield name
> > > from someothertable
> > > ;
> > >
> > A small nitpick, but technically the definition by Elmasri and Navathe
> uses
> > "store date" as part their definition. You are demonstrating an SQL
> > expression as a means of contradiction. Trivial, I know, but still
their
> > definition holds until you at least find another example that would
> indicate
> > a base table doesn't meet the criteria given.
>
> Prepend "CREATE VIEW" above.
>
>
To the user, the "virtual table" would still logically have columns distinguishable by name. Moreover, a view is not a base table - it's a symbol for a relational or SQL expression.
No need to reply, as I don't see any real value in arguing this point. I concede that the SQL standard and that the various commercial implementations are not perfect in attaining a pure or even decent representation of the relational model; though, as Mr. Tuuri points out, quite a few variants of the "model" have evolved, leaving one to ask, will the real relational model please stand up.
Thanks,
Dan Received on Mon Aug 25 2003 - 08:16:07 CEST