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Re: '= NULL' is not the same as 'IS NULL'

From: Mark Morgan Lloyd <markMLl(dot)pgsql-odbc(at)telemetry(dot)co(dot)uk>
To: pgsql-odbc(at)postgresql(dot)org
Subject: Re: '= NULL' is not the same as 'IS NULL'
Date: 2006-09-06 20:40:50
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-odbc
Geert Janssens wrote:

> I tried this query directly in phpPgSQL, and indeed it returns no results. On
> the other hand, if I modify "imgname" = NULL to "imgname" IS NULL, the query
> works fine.
> Has anybody else stumbled upon this issue ?

I'm afraid so, in Joe Celko's "SQL for Smarties" book, after which I simply
accepted that that was the way SQL worked. He also comments on the IS TRUE etc.
form which I see PostgreSQL now supports, also in the relevant section of the
manual I see IS DISTINCT FROM which might help.

Mark Morgan Lloyd
markMLl .AT. .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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