From: Daniel CAUNE <d.caune@free.fr>
To: pgsql-sql@postgresql.org
Subject: Constraint UNIQUE on a column not case sensitive
Date: Sat, 01 Jul 2006 09:47:59 -0400
Message-ID: <0J1Q008ME8ZX7M90@VL-MO-MR003.ip.videotron.ca> (raw)
Hi,
I would like to find an efficient solution for adding/implementing a constraint UNIQUE on a VARCHAR column not case sensitive:
ALTER TABLE MyTable
ADD CONSTRAINT UNQ_MyTable_MyColumn
UNIQUE (lower(MyColumn)); -- invalid syntax
The idea is to have an index on that column, in a not case sensitive form, i.e. lower(MyColumn).
SELECT *
FROM MyTable
WHERE lower(MyColumn) = lower('...');
I don't know how to add such a constraint on MyTable except by defining a trigger on INSERT clause and checking whether lower(:NEW.MyColumn) has been already inserted in MyTable.
Is there better and more efficient way to do that?
Regards,
--
Daniel
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To: pgsql-sql@postgresql.org
Cc: d.caune@free.fr
Subject: Re: Constraint UNIQUE on a column not case sensitive
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