pg.ddx.io pgsql-sql@postgresql.org mailing list archive
help / color / mirror / Atom feedFrom: Adrian Klaver <adrian.klaver@gmail.com>
To: Vik Fearing <vik.fearing@dalibo.com>
Cc: ldrlj1 <russelljanusz@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: table constraint on two columns
Date: Mon, 22 Jul 2013 07:44:54 -0700
Message-ID: <51ED4566.8060005@gmail.com> (raw)
In-Reply-To: <51ED3ECB.5020703@dalibo.com>
References: <1374501921767-5764645.post@n5.nabble.com>
<51ED3ECB.5020703@dalibo.com>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-sql>
On 07/22/2013 07:16 AM, Vik Fearing wrote:
> On 07/22/2013 04:05 PM, ldrlj1 wrote:
>> Postgres 9.2.4.
>>
>> I have two columns, approved and comments. Approved is a boolean with no
>> default value and comments is a character varying (255) and nullable.
>>
>> I am trying to create a constraint that will not allow a row to be entered
>> if approved is set to false and comments is null.
>
> CHECK constraints work on positives, so restate your condition that
> way. A row is permissible if approved is true or the comments are not
> null, correct? So...
>
> ...add constraint chk_comments (approved or comments is not null)...
>
>> This does not work. yada, yada, yada... add constraint "chk_comments' check
>> (approved = false and comments is not null). The constraint is successfully
>> added, but does not work as I expected.
>
> That's not the same check as what you described.
An additional comment, did you put the check constraint on a column or
the table?
From the docs:
http://www.postgresql.org/docs/9.2/interactive/sql-createtable.html:
.. A check constraint specified as a column constraint should reference
that column's value only, while an expression appearing in a table
constraint can reference multiple columns...
>
>
--
Adrian Klaver
adrian.klaver@gmail.com
--
Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-sql
view thread (4+ messages) latest in thread
Message-ID: <51ED4566.8060005@gmail.com>
Permalink: ../51ED4566.8060005@gmail.com/
Also on: postgresql.org/message-id/51ED4566.8060005@gmail.com
reply
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: adrian.klaver@gmail.com, vik.fearing@dalibo.com, russelljanusz@yahoo.com
Subject: Re: table constraint on two columns
In-Reply-To: <51ED4566.8060005@gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox