Re: Examples of SQL anomalies?

From: JOG <jog_at_cs.nott.ac.uk>
Date: Mon, 7 Jul 2008 13:21:20 -0700 (PDT)
Message-ID: <089e3f31-361b-4bca-af30-7d5022ffd48b_at_f36g2000hsa.googlegroups.com>


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. 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. Received on Mon Jul 07 2008 - 22:21:20 CEST

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