RE: Adding another subfield to an externally defined data structu re.

["Joe Giusto" <jgiusto@xxxxxxxxxxxxxx>]

rob@xxxxxxxxx wrote:
> Overlaying an array.
>
>      D FLWORKREC       DS                  likerec(flworkr)
>      D pDuh            s               *   inz(%addr(flworkrec))
>      D duh             ds                  based(pDuh)
>      D  col                          15p 4 overlay(duh:39) dim(389)
>
> Rob Berendt

<snip> One problem is that any workaround (easy or not) is fraught with
certain dangers.  For example, if the field layout happens to change, the
overlay may become invalid.
<snip>

could pDuh be defined as inz(%addr(arrayfld))
if so, it would not matter if the layout changes, only if the arrayfld size
changes.


Joe Giusto II
Programmer/Analyst
Ritz Camera
Beltsville, MD
301-419-3209 x347
410-813-2812 x347

 -----Original Message-----
From:   rpg400-l-bounces+jgiusto=ritzcamera.com@xxxxxxxxxxxx
[mailto:rpg400-l-bounces+jgiusto=ritzcamera.com@xxxxxxxxxxxx]  On Behalf Of
Hans Boldt
Sent:   Tuesday, April 29, 2003 1:09 PM
To:     rpg400-l@xxxxxxxxxxxx
Subject:        Re: Adding another subfield to an externally defined data 
structu
re.

rob@xxxxxxxxx wrote:
> Overlaying an array.
>
>      D FLWORKREC       DS                  likerec(flworkr)
>      D pDuh            s               *   inz(%addr(flworkrec))
>      D duh             ds                  based(pDuh)
>      D  col                          15p 4 overlay(duh:39) dim(389)
>
> Rob Berendt

Rob: Maybe I'm a little thick today, but doesn't that code fragment
accomplish what you want?

I guess this all goes back to the decision in DDS not to support
arrays in records. The argument goes that arrays should be
implemented in tables, not within individual rows, in a relational
database (ignoring the fact that some RDBMS's do allow arrays within
rows).

So the question becomes, should a programming language make it easy
to get around a design limitation in the database? One problem is
that any workaround (easy or not) is fraught with certain dangers.
For example, if the field layout happens to change, the overlay may
become invalid.

The bottom line is that if EXTNAME suits your purposes better than
LIKEREC, then continue to use it.

Cheers! Hans


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