From: Gera Mel Handumon <geramel.h@gmail.com>
To: Michael Glaesemann <grzm@seespotcode.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: NULLIF problem
Date: Thu, 29 Nov 2007 17:43:38 +0800
Message-ID: <474404120711290143g6ef15a73j9363b2b95882f043@mail.gmail.com> (raw)
In-Reply-To: <17DF2022-C1D2-4D9E-ABAC-DC3F5B20FBE7@seespotcode.net>
References: <474404120711271804y21b8e0b3j7f4b3771c088a82a@mail.gmail.com>
<17DF2022-C1D2-4D9E-ABAC-DC3F5B20FBE7@seespotcode.net>
Thanks!
On Nov 28, 2007 10:47 AM, Michael Glaesemann <grzm@seespotcode.net> wrote:
>
> On Nov 27, 2007, at 21:04 , Gera Mel Handumon wrote:
>
> > I encounter an error if i use NULLIF with timestamp with time zone.
> > eq. dbtime=nullif(mytime,'')
> >
> > i want to null the value of field DBTIME if the variable mytime=" "
> >
> > DBTIME ="timestamp with time zone" datatype
> >
> > error: column DBTIME is of type timestamp with time zone but
> > expression is of type text.
>
> I believe the reason is that '' is not a valid timestamp value: think
> of it this way:
>
> IF mytime = '' THEN
> mytime := NULL;
> END IF;
>
> The first thing it needs to do is compare the mytime value with ''.
> As '' is not a valid timestamp value, it may be casing mytime to
> text. You'll run into problems if you're assigning a text value to a
> timestamp field (which happens after the initial comparison--and the
> cast--are done.)
>
> I think you may need to handle this is you middleware, or handle the
> IF THEN explicitly in a function. Maybe CASE would work:
>
> CASE WHEN mytime = '' THEN NULL
> ELSE CAST(mytime AS TIMESTAMP)
> END
>
> Michael Glaesemann
> grzm seespotcode net
>
>
>
--
Gera Mel E. Handumon
Application Programmer
PaySoft Solutions, Inc.
-----------------------------------------------------------------
"Share your knowledge. It's a way to achieve immortality" - Dalai Lama
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-sql@postgresql.org
Cc: geramel.h@gmail.com, grzm@seespotcode.net
Subject: Re: NULLIF problem
In-Reply-To: <474404120711290143g6ef15a73j9363b2b95882f043@mail.gmail.com>
* 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