Re: Unique constraint and NULL values

"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!)
>
> if i'm creating a UNIQUE constraint, my goal is to disallow values that
> are known to be equal to other known values -- so, it's entirely
> appropriate to not disallow (sorry for the double-negs) unknown values
> (triple-negs?) since there is no known basis for excluding them

But then why does it exclude them when there are other columns present?

Xho

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