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

He's talking about the difference between an inline constraint and an out-of-line constraint (or, indeed, a constraint that is added later via an alter table command, which is about as out-of-line as it is possible to be).

I can see why they appear to be table level constraints... the command is, after all, 'alter table'. Try being a little more charitable.

Anyway, Vishalm, a constraint is a constraint is a constraint. No difference anywhere or any how they're applied.

Regards
HJR

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"damorgan" <dan.morgan_at_ci.seattle.wa.us> wrote in message
news:3C768631.F22ABEB6_at_ci.seattle.wa.us...


> 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)

>