From: Markus Bertheau <twanger@bluetwanger.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Stephan Szabo <sszabo@megazone.bigpanda.com>
Cc: Richard Huxton <dev@archonet.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: multi column foreign key for implicitly unique columns
Date: Tue, 17 Aug 2004 16:57:38 +0200
Message-ID: <1092754658.2627.32.camel@dicaprio.akademie1.de> (raw)
In-Reply-To: <4307.1092753995@sss.pgh.pa.us>
References: <1092734724.2627.4.camel@dicaprio.akademie1.de>
<4121D55D.1040105@archonet.com>
<20040817072443.S60684@megazone.bigpanda.com>
<4307.1092753995@sss.pgh.pa.us>
В Втр, 17.08.2004, в 16:46, Tom Lane пишет:
> I think one reason for this is that otherwise it's not clear which
> unique constraint the FK constraint depends on. Consider
>
> create table a (f1 int unique, f2 int unique);
>
> create table b (f1 int, f2 int,
> foreign key (f1,f2) references a(f1,f2));
>
> How would you decide which constraint to make the FK depend on?
Either way, the semantics are the same, right?
--
Markus Bertheau <twanger@bluetwanger.de>
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To: pgsql-sql@postgresql.org
Cc: twanger@bluetwanger.de, tgl@sss.pgh.pa.us, sszabo@megazone.bigpanda.com, dev@archonet.com
Subject: Re: multi column foreign key for implicitly unique columns
In-Reply-To: <1092754658.2627.32.camel@dicaprio.akademie1.de>
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