Re: Implementing Constraints

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Sun, 1 Jul 2001 09:19:06 +0200
Message-ID: <tjtjjc2enkts5e@beta-news.demon.nl>

"Victor" <lch_1_at_hotmail.com> wrote in message news:9hmg7e$7qh41_at_imsp212.netvigator.com...
> Dear all,
>
> In the oracle book, i found the following syntax in defining the
constraint:
>
> column dataytpe {CONSTRAINT constraint]
> in_line_constraint
> [defer_spec]
> in_line_constraint :==
> {[NOT] NULL
> | PRIMARY KEY
> .
> .
> .
> defer_spec :==
> [NOT DEFERRABLE | DEFERRABLE [INITIALLY {IMMEDIATE | DEFERRED}]
> .
> .
>
> I don't understand why the DEFERABLE syntax can be used with the IMMEDIATE
> syntax. From the book, the use of IMMEDIATE syntax indicate that the
default
> is to check this constraint at the end of every DML statement. But
> DEFFERABLE means check when COMMIT.
> It makes me confuse
>
> THX
>
>

It says:
the constraint is deferrable i.e. it *can* be deferred and *initially* it is immediate
or *initially* it is deferred
which means: you can change that in a later stage.

Hth,

Sybrand Bakker, Oracle DBA Received on Sun Jul 01 2001 - 02:19:06 CDT