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From: sad <sad@bankir.ru>
Organization: IT
To: =?iso-8859-1?q?K=D6PFERL=20Robert?= <robert.koepferl@sonorys.at>
Subject: Re: Single row tables
Date: Wed, 12 Jan 2005 09:39:59 +0300
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On Tuesday 11 January 2005 17:45, K=D6PFERL Robert wrote:
> Hi,
>
> with what constraint or how can I ensure that one of my tables has exac=
t
> one record or 0..1 records?

A trigger procedure BEFORE INSERT would help you.

And a column type with only one possible field value would help you if yo=
u=20
define UNIQUE INDEX on a field of this (user-defined) type.