Re: Examples of SQL anomalies?
From: Keith H Duggar <duggar_at_alum.mit.edu>
Date: Mon, 7 Jul 2008 19:42:33 -0700 (PDT)
Message-ID: <2cc5989c-abf3-4c8c-a479-1c61c7b38bc3_at_m36g2000hse.googlegroups.com>
Date: Mon, 7 Jul 2008 19:42:33 -0700 (PDT)
Message-ID: <2cc5989c-abf3-4c8c-a479-1c61c7b38bc3_at_m36g2000hse.googlegroups.com>
CELKO wrote :
> Marshall wrote :
> > False! It's not from nothing, and it's not simply a convention.
> > It's the identity of the operator being aggregated. <<
>
> Yes, zero is the additive identity. But this is a convention used to
> get rid of the empty set problem and preserve easy computations.
Yes, sum[{}] = 1 eliminates problems and makes computation easier. It's a shame that SQL offers neither of those benefits.
KHD Received on Tue Jul 08 2008 - 04:42:33 CEST