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Re: Single row tables - Mailing list pgsql-sql

From sad
Subject Re: Single row tables
Date
Msg-id 200501120939.59489.sad@bankir.ru
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In response to Single row tables  (KÖPFERL Robert <robert.koepferl@sonorys.at>)
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On Tuesday 11 January 2005 17:45, KÖPFERL Robert wrote:
> Hi,
>
> with what constraint or how can I ensure that one of my tables has exact
> 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 you
define UNIQUE INDEX on a field of this (user-defined) type.

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