Re: Unique constraint and NULL values

Am Fri, 22 Oct 2004 08:33:52 -0500 schrieb Turkbear <john.g_at_dot.spamfree.com>:
> It can get almost metaphysical, but:
> Identifying a column which has an undeterminable value ( NULL) is not
> the same as identifying that value, so being able to
> consider that column unique ( that is , it is the only one with the
> undeterminable value) is not a problem.
>

The difference you point to is clear for me. But i did not find a real world example for a column which is unique in a table and at most one row with a NULL value for this column should be allowed.

-- 
Frank Piron,
etfrankatkonaddotn
(leftrotate two)