Re: NULLIF problem

Thanks!

On Nov 28, 2007 10:47 AM, Michael Glaesemann <grzm(at)seespotcode(dot)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.
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