Re: Difference between table level and column level NOT NULL constraint?

On 22 Feb 2002 09:08:53 -0800, vishalnm_at_yahoo.com (Vishalm) wrote:

>Hi,
>
>What is the difference between table level and column level NOT NULL
>constraint?
>
>for e.g.a not null constraint can be defined in the foll ways
>
>1)
>
>Create table test
>(testnull VARCHAR2(10) NOT NULL)
>
>2)
>
>Create table test
>(testnull VARCHAR2(10));
>
>ALTER TABLE ADD CHECK (testnull NOT NULL);
>
>Is there any difference in the way Oracle does validation for the
>above defined constraint methods or are there any performance
>differences?
>
>Thanx in advance.
>
>regards,
>Pradeep
>
>(Pls cc ur response to : pradeep.mittal_at_iflexsolutions.com)

There is no difference. The only reason to have a table level not null check constraint is you want to avoid system generated names. That can be useful when you want to derive end user-friendly error messages from your exceptions.
IMO this means it is pretty useless to define a table level check constraint with a system generated name.

Regards

Sybrand Bakker, Senior Oracle DBA

To reply remove -verwijderdit from my e-mail address Received on Fri Feb 22 2002 - 11:52:46 CST