Re: Select * into an external DS, and then adding columns

Hi Rob,

I would swear that ~12 years ago I fielded a support issue where SELECT *
was used in RPG, the table was modified, the program was not altered or
recompiled, and it failed in production.

Given that was so long ago, it could just be my memory playing tricks on me.

I think at some point, the RPG SQL pre-compiler was changed, when SELECT *
is present, to go out and fetch the list of columns at RPG pre-compile
time and hard code the current list of columns in the program. I just
learned of that this week. Nice change imo, but it still is not a good
idea to use SELECT * in programs, except in some rare cases.

Mike

date: Fri, 5 Feb 2016 13:45:51 -0500

from: rob@xxxxxxxxx
subject: Select * into an external DS, and then adding columns

Scenario:

You have something like this:
D RCODS E DS EXTNAME(RCO)
C/EXEC SQL
C+ DECLARE C CURSOR FOR
C+ SELECT * FROM RCO
C+ WHERE CMPNY BETWEEN :
C+ W1LWCO AND :W1UPCO AND CRSTS = 'A'
C+ ORDER BY CMPNY FOR FETCH ONLY
C/END-EXEC
C/EXEC SQL
C+ OPEN C
C/END-EXEC
C/EXEC SQL
C+ FETCH C INTO :RCODS
C/END-EXEC
You add a column to the table, and do NOT recompile this program.
Therefore the external DS doesn't match.
ALTER TABLE RCO
ADD COLUMN ...

I thought (many releases ago) that this used to generate a mild warning.
Then it became a hard halt.
I just tried it with seclvl 0 logging and STRDBG running and no warning
whatsoever. The data came from the cursor and worked just fine.

Rob Berendt