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

there is no such thing as a TABLE LEVEL not null. A not null column is a not null column. They are all defined as a check constraint.

Daniel Morgan

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)
Received on Fri Feb 22 2002 - 11:55:39 CST