From: Bruce Momjian <maillist@candle.pha.pa.us>
Message-Id: <199806270211.WAA17393@candle.pha.pa.us>
Subject: Re: [SQL] isnull function]
To: kachun@pathlink.com (Kachun Lee)
Date: Fri, 26 Jun 1998 22:11:56 -0400 (EDT)
Cc: hackers@postgreSQL.org (PostgreSQL-development)
In-Reply-To: <3.0.1.32.19980626133317.006bc8cc@rr.pathlink.com> from "Kachun
	Lee" at Jun 26, 98 01:33:17 pm
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
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> 
> 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?
> 
> 

Having DateTime* be a NULL does not represent a NULL value in SQL
internally.

Not sure how to do it, because I don't rememeber where the NULL checking
is done.

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