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From: Daniel Verite <daniel@manitou-mail.org>
To: Max Pyziur <pyz@brama.com>
Cc: pgsql-interfaces@postgresql.org
Subject: Re: binding a variable to NULL in perl-DBD
Date: Thu, 22 Aug 2013 22:48:55 +0200
Message-ID: <ceef0d9a-f613-4196-bc9c-b5e90ebcd35e@mm> (raw)
In-Reply-To: <alpine.LRH.2.03.1308211655440.1058@brama.com>
List-Unsubscribe:  <mailto:majordomo@postgresql.org?body=unsub%20pgsql-interfaces>

	Max Pyziur wrote:

> I'm trying to determine how to pass "NULL" to a variable, specifically in 
> the conditional section of a SQL statement:
> 
> SELECT moo
> FROM foo aa
> WHERE field1 = ?
> AND field2 = ?

Perl's undef is used to pass NULL as a literal but field=NULL
will never be true.

> SELECT moo
> FROM foo aa
> WHERE field1 = 'goo'
> AND field2 IS NULL

You may use:
WHERE field1 = ?
AND field2 IS NOT DISTINCT FROM ?

which conveys the idea that field2 must be equal to the value passed,
and works as expected with both non-NULL literals and NULL (undef).

Best regards,
-- 
Daniel
PostgreSQL-powered mail user agent and storage: http://www.manitou-mail.org


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  Subject: Re: binding a variable to NULL in perl-DBD
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