Debugging RPGIV program used by SQL UDF (was Extraction problem)

All -

I found the INCR function and program in Ted Holt's article (in the itjungle link below) to be useful. Now I'm trying to debug it, to no avail. What is required to debug a program like this one - that is run as the result of a SQL user-defined function call?

Regards,
sjl

----- Original Message ----- From: "McGovern, Sean" <Sean.McGovern@xxxxxxxxxxxx>
To: "RPG programming on the AS400 / iSeries" <rpg400-l@xxxxxxxxxxxx>
Sent: Wednesday, October 03, 2007 8:52 AM
Subject: RE: Extraction problem

In the following SQL, I've assumed that file QSYS/QADBIFLD has more than
99999 records and have also used the INCR function (see
http://www.itjungle.com/fhg/fhg121405-story01.html): -

with
alpha as
(select 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' alpha from qsqptabl),
seq as
(select incr(0) as seq
from qsys/qadbifld fetch first 99999 rows only),
char1 as
(select substr(alpha,seq,1) as char
from alpha, seq fetch first 26 rows only),
char2 as
(select substr(alpha,seq,1) as char
from alpha, seq fetch first 26 rows only),
allcat as
(select a.char concat b.char
concat digits(cast(seq as dec(5))) as cat
from char1 a, char2 b, seq)
select * from allcat
where not exists
(select 1 from yourcataloguefile where cat=yourcataloguefield)

You will also need to add your own selection criteria (numbers available
between etc.).

Regards,
Sean McGovern