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From: joel garry on 8 Dec 2009 19:12
On Nov 30, 8:52 pm, Ben Finney <bignose+hates-s...(a)benfinney.id.au>
wrote:
> Gene Wirchenko <ge...(a)ocis.net> writes:
> > On Tue, 01 Dec 2009 13:45:44 +1100, Ben Finney
> > <bignose+hates-s...(a)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
--
@home.com is bogus.
http://www.signonsandiego.com/news/2009/dec/07/man-gets-18-months-in-prison-for-computer-fraud/
From: Ben Finney on 8 Dec 2009 19:38
joel garry <joel-garry(a)home.com> writes:

> On Nov 30, 8:52 pm, Ben Finney <bignose+hates-s...(a)benfinney.id.au>
> wrote:
> > 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:
[…]

Yes, that about covers it. While 'ORDER BY' produces something that
isn't a relation, it clearly is an operation useful enough that it
belongs in a relational DBMS.

--
\ “If you do not trust the source do not use this program.” |
`\ —Microsoft Vista security dialogue |
_o__) |
Ben Finney
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