agora inbox for pgsql-sql@postgresql.org
help / color / mirror / Atom feedFrom: Tom Lane <tgl@sss.pgh.pa.us>
To: Andreas Kretschmer <akretschmer@spamfence.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: unique constraint definition within create table
Date: Wed, 02 Dec 2015 09:46:09 -0500
Message-ID: <14838.1449067569@sss.pgh.pa.us> (raw)
In-Reply-To: <20151202063621.GA5526@tux>
References: <20151202063621.GA5526@tux>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-sql>
Andreas Kretschmer <akretschmer@spamfence.net> writes:
> i'm trying to create a table with 2 int-columns and a constraint that a
> pair of (x,y) cannot be as (y,x) inserted:
> test=# create table foo(u1 int,u2 int, unique (least(u1,u2),greatest(u1,u2)));
> ERROR: syntax error at or near "("
> LINE 1: create table foo(u1 int,u2 int, unique (least(u1,u2),greates...
> I know, i can solve that in this way:
> test=*# create table foo(u1 int,u2 int);
> CREATE TABLE
> test=*# create unique index idx_foo on foo(least(u1,u2),greatest(u1,u2));
> CREATE INDEX
> But is there a way to define the unique constraint within the create table - command?
No. Per SQL standard, the argument of a UNIQUE (or PRIMARY KEY)
constraint can only be a list of column names.
We would consider relaxing that, except it would break the
information_schema views for such constraints.
regards, tom lane
--
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 (6+ messages) latest in thread
Message-ID: <14838.1449067569@sss.pgh.pa.us>
Permalink: ../14838.1449067569@sss.pgh.pa.us/
Also on: postgresql.org/message-id/14838.1449067569@sss.pgh.pa.us
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: tgl@sss.pgh.pa.us, akretschmer@spamfence.net
Subject: Re: unique constraint definition within create table
In-Reply-To: <14838.1449067569@sss.pgh.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox