A little testing shows that neither Bruce nor I got it exactly right.  

I implied that a field must consist of all NULs in order for QUERY to
report 'NULL ITEM'.  That is not true.  Counterexample:
"\0\0\0\0\0VWXYZ".  (Please excuse the C notation.)

Bruce opined that if any character in the field is NUL, QUERY reports
'NULL ITEM'.  This is not true.  Counterexample:  "ABCDE\0\0\0\0\0".

The truth is out there.

Walter   

Walter J. Murray  

-----Original Message-----
From: Bruce Collins [mailto:[log in to unmask]] 
Sent: Wednesday, December 14, 2005 12:09 PM
To: Walter Murray; [log in to unmask]
Subject: Re: [HP3000-L] Adding a "Null Item"

Walter Murray was the first to point out:
> The original poster asked how to generate a "null item" in an IMAGE
> field.
>
> I think some of the responses have played fast and loose with the term
> "null item".  The first thing you have to do is define exactly what
you
> mean by that.

<snip>

>On a character field, such as type X, I think QUERY reports
> "NULL ITEM" if ALL characters in the field are the ASCII character
NUL,
> that is, the character with the numeric value of 0.

That's what I would think of as a "NULL" item, but I don't think it is
what 
QUERY is reporting as "NULL ITEM". I think you see this reported if ANY
of 
the characters are NULL (or maybe just non-printable). At a site where I

once worked they had a distressing tendency to redefine a few bytes here
and 
there in IMAGE character items as integers. IMAGE will gladly store them
and 
retrieve them fine, but in QUERY all that you would ever see is "NULL
ITEM".

Bruce 

* To join/leave the list, search archives, change list settings, *
* etc., please visit http://raven.utc.edu/archives/hp3000-l.html *