Date: Mon, 22 Mar 2004 11:26:59 +0100
From: Erik Thiele <erik@thiele-hydraulik.de>
To: Achilleus Mantzios <achill@matrix.gatewaynet.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: special integrity constraints
Message-Id: <20040322112659.4553df76.erik@thiele-hydraulik.de>
In-Reply-To: <Pine.LNX.4.44.0403221212500.31407-100000@matrix.gatewaynet.com>
References: <20040322102031.6a6f0b77.erik@thiele-hydraulik.de>
	<Pine.LNX.4.44.0403221212500.31407-100000@matrix.gatewaynet.com>
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On Mon, 22 Mar 2004 12:13:29 +0200 (EET)
Achilleus Mantzios <achill@matrix.gatewaynet.com> wrote:

> O kyrios Erik Thiele egrapse stis Mar 22, 2004 :
>=20
> Did you check out the DEFERRABLE option on the constraint?
>=20

DEFERRABLE
NOT DEFERRABLE

This controls whether the constraint can be deferred. A constraint that
is not deferrable will be checked immediately after every command.
Checking of constraints that are deferrable may be postponed until the
end of the transaction (using the SET CONSTRAINTS command). NOT
DEFERRABLE is the default.=20

!!!! Only foreign key constraints currently accept
this clause. All other constraint types are not deferrable. !!!!

my constraint is not a foreign key constraint....

cya!
erik

> > hi,
> >=20
> > i have two tables
> >=20
> > create table a (x integer);
> > create table b (y real);
> >=20
> > i have the special constraint that the sum of the number of rows in
> > table a plus the number of rows in table b must be even.
> >=20
> > so there is a posibility of adding one element to a and one element
> > to b, and again the constraint is met.
> >=20
> > but this of course does not work, since between adding the element
> > to a and adding the element to b, the constraint is not met.
> >=20
> > so i cannot use a trigger.
> >=20
> > what i need is the execution of a check procedure at commit time. is
> > that somehow possible?
> >=20
> > my database has much more tables than just a and b, and most time
> > the other tables are modified and not a or b, so it would be nice to
> > execute the constraint checking procedure only if a or b was
> > modified.
> >=20
> > yes :) this question i asked in my former mail too, but I think it
> > looked like there was a workaround and my problem was wrong. so i
> > created this new kind of problem here to make things clearer.
> >=20
> >=20
> > cu
> > Erik
> >=20
> >=20
> >=20
>=20
> --=20
> -Achilleus
>=20


--=20
Erik Thiele
Horst Thiele Maschinenbau-Hydraulische Ger=E4te GmbH
Im Kampfrad 2 - 74196 Neuenstadt
Tel.: 07139/4801-19
Fax.: 07139/4801-29
email: erik@thiele-hydraulik.de
Internet: http://www.thiele-hydraulik.de/