Re: UNIQUE and NULL in SQL

> What would be the rationale behind UNIQUE if it was any different to
> this? That is, what makes the first NULL different to your second
> NULL?
>

NULL is not equal to NULL. NULL is also not unequal to NULL.

If the test is NULL = NULL, the result is NULL. If the test is NULL <> NULL, the result is NULL.

--
Regards,
    David Cressey
    www.dcressey.com