Re: The job of a relational DBMS
From: joel garry <joel-garry_at_home.com>
Date: Tue, 8 Dec 2009 16:12:04 -0800 (PST)
Message-ID: <39cd32d0-fc0a-4e59-b0f6-034ab383a840_at_s21g2000prm.googlegroups.com>
On Nov 30, 8:52 pm, Ben Finney <bignose+hates-s..._at_benfinney.id.au> wrote:
> Gene Wirchenko <ge..._at_ocis.net> writes:
> > On Tue, 01 Dec 2009 13:45:44 +1100, Ben Finney
> > <bignose+hates-s..._at_benfinney.id.au> wrote:
> > >What I was trying to express was that relational operations — like
> > >the various relational operations that ‘SELECT’ implements — should
> > >only return data as relations (they might also return status
> > >responses). They should never return non-relation data.
>
> > A relation does not have order. This would not be a relation
> > select clicode,cliname from clients order by clicode
> > because of the order by clause.
>
> Hmm. I'm not sure it's right to say the result would not *be* a
> relation; but I certainly take the point about ‘ORDER BY’ requesting
> order be imposed on an orderless relation.
Date: Tue, 8 Dec 2009 16:12:04 -0800 (PST)
Message-ID: <39cd32d0-fc0a-4e59-b0f6-034ab383a840_at_s21g2000prm.googlegroups.com>
On Nov 30, 8:52 pm, Ben Finney <bignose+hates-s..._at_benfinney.id.au> wrote:
> Gene Wirchenko <ge..._at_ocis.net> writes:
> > On Tue, 01 Dec 2009 13:45:44 +1100, Ben Finney
> > <bignose+hates-s..._at_benfinney.id.au> wrote:
> > >What I was trying to express was that relational operations — like
> > >the various relational operations that ‘SELECT’ implements — should
> > >only return data as relations (they might also return status
> > >responses). They should never return non-relation data.
>
> > A relation does not have order. This would not be a relation
> > select clicode,cliname from clients order by clicode
> > because of the order by clause.
>
> Hmm. I'm not sure it's right to say the result would not *be* a
> relation; but I certainly take the point about ‘ORDER BY’ requesting
> order be imposed on an orderless relation.
Should anyone care, I ran across this while meditating upon Chris Date
giving a seminar in Dallas next month:
http://books.google.com/books?id=406_pJtiJ6sC&pg=PT175&lpg=PT175&dq=%22What+about+ORDER+BY%3F%22+chris+date&source=bl&ots=xXj0qFAVr9&sig=MH2zmtp51-x1BtSjgYBJO4MCcLc&hl=en&ei=ougeS8axMYbAsQPT9qX3CQ&sa=X&oi=book_result&ct=result&resnum=1&ved=0CAgQ6AEwAA#v=onepage&q=&f=false
>
jg
-- _at_home.com is bogus. http://www.signonsandiego.com/news/2009/dec/07/man-gets-18-months-in-prison-for-computer-fraud/Received on Tue Dec 08 2009 - 18:12:04 CST