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From: Raphael Bauduin <raphael(dot)bauduin(at)be(dot)easynet(dot)net>
To: Artur Pietruk <arturp(at)plukwa(dot)pdi(dot)net>
Cc: Raphael Bauduin <raphael(at)be(dot)easynet(dot)net>,pgsql-admin(at)postgresql(dot)org
Subject: Re: CREATE TABLE AS ...
Date: 2002-07-24 08:14:17
Message-ID: 20020724081417.GA7419@raphael (view raw, whole thread or download thread mbox)
Lists: pgsql-admin

Thanks for the tips, but although the result is the same as a primary
key constraint, I'm not sure it will fit my needs as I want to use the
primary key in a foreign key constraint in another table. I made it with
a copy and it works fine.


On Tue, Jul 23, 2002 at 04:40:32PM +0200, Artur Pietruk wrote:
> On Tue, Jul 23, 2002 at 03:48:07PM +0200, Raphael Bauduin wrote:
> > Hi,
> 	Hello,
> > In a data model change, I wanted to use the "create table as select"
> > feature. However, I want that table to have a primary key defined, and
> > thus a field defined as NOT NULL. I didn't find a way to add a NOT NULL
> > constraint on a column of an existing table. If there isn't, what's the
> > best way to go? A COPY?
> 	Yes, it looks that you cannot add NOT NULL constraint. But check if
> this could work for you:
> == 8< ===
> ALTER TABLE your_table ADD CONSTRAINT my_constr1 CHECK (your_column IS NOT NULL UNIQUE);
> ALTER TABLE your_table ADD CONSTRAINT my_constr2 UNIQUE (your_column);
> == 8< ===
> 	It is not marked as "Primary Key", but it does the same job: checks
> that column is UNIQUE and NOT NULL.
> 	Best regards,
> -- 
> --- Artur Pietruk, arturp(at)plukwa(dot)net

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