Re: [GENERAL] FOREIGN KEY syntax

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Oliver Elphick <olly(at)lfix(dot)co(dot)uk>
Cc: pgsql-general(at)postgreSQL(dot)org, olly(at)linda(dot)lfix(dot)co(dot)uk
Subject: Re: [GENERAL] FOREIGN KEY syntax
Date: 2000-03-07 03:00:31
Message-ID: 200003070300.WAA02732@candle.pha.pa.us
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Oliver Elphick wrote:

> Andrzej Mazurkiewicz wrote:
> >> And what is MATCH FULL?
> > [Andrzej Mazurkiewicz] I would not like to speculate perhaps
> >somebody else knows exact answer.
>
> MATCH FULL:
> Either all referencing columns must be null, or all must have values.
>
> MATCH PARTIAL:
> "if any columns are non-null, there must be at least one row in the
> referenced table that could satisfy the constraint if the other null
> values were correctly substituted."

As I read the SQL3 spec draft, it's that if at least one
of the columns is NULL, no check is done at all.

Could be wrong, will lookup at Thursday when back in
Hamburg.

Jan from Philly

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