# Re: Limits

From: JOG <jog_at_cs.nott.ac.uk>

Date: Fri, 25 Jul 2008 14:58:38 -0700 (PDT)

Message-ID: <7a205ced-bd9c-47b9-8320-63200e13fed7_at_f63g2000hsf.googlegroups.com>

Date: Fri, 25 Jul 2008 14:58:38 -0700 (PDT)

Message-ID: <7a205ced-bd9c-47b9-8320-63200e13fed7_at_f63g2000hsf.googlegroups.com>

On Jul 25, 7:04 pm, Tegiri Nenashi <TegiriNena..._at_gmail.com> wrote:

> On Jul 25, 7:30 am, JOG <j..._at_cs.nott.ac.uk> wrote:

*>
**> > As it is with ORDER BY I guess, which is supposed to spit out a linear
**> > ordering where only a partial ordering may exist.
**>
**> Could you please be more specific? All SQL datatypes I know (well,
**> those that I'm using -- string, number, date) are total orders. What
**> partial ordered datatype do you have in mind?
*

the tuple itself. For instance if we have relation: R := {w, x, y}

w := (a:1, b:1) x := (a:2, b:2) y := (a:3, b:2)

then "ordering by a" yields a total ordering over R: {(w, x), (w,y), (x,y)}

but "ordering by b" gives the partial ordering: {(w, x), (w,y)}

Regards, J. Received on Fri Jul 25 2008 - 23:58:38 CEST