From: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: Scott Whitney <swhitney@journyx.com>
To: pgsql-admin@postgresql.org
Subject: Re: Strange query problem...
Date: Wed, 28 Jan 2009 12:05:20 -0600
Message-ID: <49804A00.EE98.0025.0@wicourts.gov> (raw)
In-Reply-To: <20090128174824.B4C457E4165@mail.int.journyx.com>
References: <20090128174824.B4C457E4165@mail.int.journyx.com>
>>> "Scott Whitney" <swhitney@journyx.com> wrote:
> Um. How is this possible?
> mydb=# select * from time_recs where id_time_rec not in (select
> id_time_rec from punch_time_recs);
> (0 rows)
> Table "public.punch_time_recs"
> Column | Type | Modifiers
>
-------------------+------------------------+-------------------------------
> id_time_rec | character varying(38) |
The column in punch_time_recs is null capable. Try using NOT EXISTS.
The SQL spec requires the NOT IN to be the equivalent of a "not
equals" test for all entries, and you can't say that any given value
is not equal to NULL, since NULL can mean that there is a value but
you don't know it. The semantics of NOT EXISTS are subtly different
here -- it means there aren't any rows known to have the value.
-Kevin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-admin@postgresql.org
Cc: Kevin.Grittner@wicourts.gov, swhitney@journyx.com
Subject: Re: Strange query problem...
In-Reply-To: <49804A00.EE98.0025.0@wicourts.gov>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox