Re: Examples of SQL anomalies?
Date: Tue, 8 Jul 2008 16:28:23 -0700 (PDT)
Message-ID: <19040b82-0130-479e-ab80-dc1f1597ac02_at_56g2000hsm.googlegroups.com>
On Jul 7, 1:21 pm, JOG <j..._at_cs.nott.ac.uk> wrote:
> On Jul 5, 1:09 pm, "David Cressey" <cresse..._at_verizon.net> wrote:
>
> > "Marshall" <marshall.spi..._at_gmail.com> wrote in message
>
> >news:6ad51b62-e66a-4daa-b21c-c361fd6b22f8_at_8g2000hse.googlegroups.com...
>
> > > What can be meaningfully asked is determined by the schema.
>
> > > If the schema specifies that the weight attribute is nullable,
> > > then the question of how much a shipment weighs in total
> > > is a question that cannot be asked.
>
> > > Marshall
>
> > Bingo!
>
> However, one /can/ validly ask "please give me the minimum the
> shipment weighs" and this may still be very useful.
OK I was just having some fun there.
> This is of course
> not a defence of null markers (obviously not. its me), but rather just
> a precaution against ruling out all questions of irregular data in
> blanket fashion. Our aim should be to provide frameworks that allows
> us to ask these questions with syntactic correctness /and/ as
> parsimoniously as possible.
Sure.
Marshall Received on Wed Jul 09 2008 - 01:28:23 CEST