Posted by Hugo Kornelis on 09/25/06 22:56

On 25 Sep 2006 11:22:15 -0700, tlyczko wrote:

>Or am I better off allowing fields like this to be null in the
>tables/columns specification and enforcing data entry per se in the
>front end????

Hi Tom,

Gert-Jan answered your question about how to set the default.

But I'm glad you asked this question - in SQL, the NULL symbol is
specifically designed to signal missing data. Not everyone agrees over
the question of the normal behaviour of NULL in different situations is
really the most appropriate for a "missing value" marker. But I don't
think that you'll find anyone who would argue that '123-45-6789' will
ever behave more appropriate for "missing value" than NULL does.

So short answer - don't use a default to signify missing data, use NULL.
And make sure that you understand three-valued logic and other quirks of
the behaviour of NULL.

--
Hugo Kornelis, SQL Server MVP

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