Re: Unique constraint and NULL values
From: Frank Piron <empty_at_zero.nil>
Date: Fri, 22 Oct 2004 08:14:41 +0200
Message-ID: <opsf9cyrlkm0et4w_at_news.online.de>
Date: Fri, 22 Oct 2004 08:14:41 +0200
Message-ID: <opsf9cyrlkm0et4w_at_news.online.de>
Thu, 21 Oct 2004 11:40:48 -0400 Mark C. Stock <mcstockX_at_Xenquery .com>
wrote:
>
> yes, in theory, the SQL Server approach is more 'pure', but in practice,
> the
> Oracle approach is more practical (i'm starting to sound like yogi
> berra!)
Agreed. IMO the most plausible argument for the Oracle approach
is the observation that allowing exactly one row with a null value
in a certain column would mean that
1)
The column value is "identifying" the row (unique constraint).
2)
NULL - an undefined value - is an "identifying" value.
which does not make sense for me.
-- Frank Piron, etfrankatkonaddotn (leftrotate two)Received on Fri Oct 22 2004 - 08:14:41 CEST