Re: [SQL] isnull function] - Mailing list pgsql-sql

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@candle.pha.pa.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?