From: Michael Glaesemann <grzm@seespotcode.net>
To: Gera Mel Handumon <geramel.h@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: NULLIF problem
Date: Tue, 27 Nov 2007 21:47:36 -0500
Message-ID: <17DF2022-C1D2-4D9E-ABAC-DC3F5B20FBE7@seespotcode.net> (raw)
In-Reply-To: <474404120711271804y21b8e0b3j7f4b3771c088a82a@mail.gmail.com>
References: <474404120711271804y21b8e0b3j7f4b3771c088a82a@mail.gmail.com>
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
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To: pgsql-sql@postgresql.org
Cc: grzm@seespotcode.net, geramel.h@gmail.com
Subject: Re: NULLIF problem
In-Reply-To: <17DF2022-C1D2-4D9E-ABAC-DC3F5B20FBE7@seespotcode.net>
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