From: Bruno Wolff III <bruno@wolff.to>
To: CG <cgg007@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: empty set
Date: Fri, 9 Jun 2006 02:33:56 -0500
Message-ID: <20060609073356.GA522@wolff.to> (raw)
In-Reply-To: <20060608214012.96518.qmail@web37907.mail.mud.yahoo.com>
References: <20060608214012.96518.qmail@web37907.mail.mud.yahoo.com>
On Thu, Jun 08, 2006 at 14:40:12 -0700,
CG <cgg007@yahoo.com> wrote:
> PostgreSQL 8.1
>
> I've been trying to write a SQL prepare routine. One of the challenging
> elements I'm running into is an empty set ...
>
> "select foo from bar where foo in ? ;"
>
> What if "?" is an set with zero elements? What is the proper value to use to
> replace "?" indicating an empty set?
Something like the following suggests you can put a subquery there that returns
0 rows. I don't think that wil work for prepared queries though; so it may not
help you.
bruno=> select * from test where test in (select 1 where false);
test
------
(0 rows)
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To: pgsql-sql@postgresql.org
Cc: bruno@wolff.to, cgg007@yahoo.com
Subject: Re: empty set
In-Reply-To: <20060609073356.GA522@wolff.to>
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