Re: [SQL] isnull function]

From: Colin Dick <cdick(at)mail(dot)ocis(dot)net>
To: Kachun Lee <kachun(at)pathlink(dot)com>
Cc: pgsql-sql(at)hub(dot)org
Subject: Re: [SQL] isnull function]
Date: 1998-06-26 20:41:22
Message-ID: Pine.LNX.3.96.980626133827.20477A-100000@ocis.ocis.net
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I posted this question a while back and received a response of 'is null'
such as:

select * from try where field is null;

Will give you all entries where the field 'field' does not yet contain a
value. Works great and I hope will answer your original question.
(Now if only I could find an easy answer for mine :)

--
Colin Dick
On Call Internet Services
cdick(at)mail(dot)ocis(dot)net

On Fri, 26 Jun 1998, Kachun Lee wrote:

> At 03:13 PM 6/26/98 -0400, you wrote:
> >>
> >> Is there an isnull function avaliable in postgres, such as:
> >>
> >> select isnull(dt_field, 'now') ...
> >>
> >> Thanks
> >>
> >>
> >
> >I don't tbink so, but it would be nice. I think Ingres has it. It also
> >would not be hard to write as a loadable function.
> >
> >--
> >Bruce Momjian | 830 Blythe Avenue
> >maillist(at)candle(dot)pha(dot)pa(dot)us | Drexel Hill, Pennsylvania 19026
> > + If your life is a hard drive, | (610) 353-9879(w)
> > + Christ can be your backup. | (610) 853-3000(h)
> >
>
> I tried, but the following code does not seem to work:
>
> #include <string.h>
> #include <stdio.h>
> #include "postgres.h"
> #include "libpq-fe.h"
> #include "utils/dt.h"
>
> DateTime * is_null(DateTime *, DateTime *);
>
> DateTime * is_null (DateTime * dt, DateTime * def)
> {
> return dt ? dt : def;
> }
>
> I searched the doc/maillist, and I could not find how to test an arg for
> NULL value. Should I post this to HACKER?
>

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