From: Thrasher <thrasher@fibers.upc.es>
To: pgsql-sql@postgresql.org
Subject: Unique constraint over null values
Date: Mon, 30 Sep 2002 19:22:23 +0200
Message-ID: <3D98884F.9070704@fibers.upc.es> (raw)
Hi all,
I have a table like
CREATE TABLE a (
type CHAR (1) NOT NULL,
data1 CHAR (16) NOT NULL,
data2 CHAR (16) NULL
);
where type can be 's' for 'single' and 'x' for extended, so s should
mean that there is only the type and data1 field, and x means that all
fields are set.
How can I set a unique constraint like CHECK (type = 's' AND UNIQUE
(type, data1)) OR (type = 'x' AND UNIQUE (type, data1, data2)) ?
The documentation says that 2 NULL values are different, so no unique
constraint can be set over it.
Thanks in advance,
Thrasher
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To: pgsql-sql@postgresql.org
Cc: thrasher@fibers.upc.es
Subject: Re: Unique constraint over null values
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