> On 24/04/12 09:29, Kjell Rilbe wrote:
>
>> SQL Server UNIQUE allows only a single null.
>
> Interesting. That's one for the "Learn something new every day"
> department! It does tend to imply that SQL Server is treating NULL (a
> lack of a value) as a value in this case?

Yes. Sort of, I don't know the MSSQL internals.

Google offers a lot of discussions on that SQL-standard
compliant-breaking behaviour in SQL Server.

> Cheers,
> Norm.
>

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