RE: "Reference #"

["Booth Martin" <Booth@xxxxxxxxxxxx>]

Then pseudorandom is fine.  
 
Anything that does not rely on sequencing would work. A 10 digit number
would have 9,999,999,999 possibilities; more than enough for most
applications and only 10 characters long.  One program with one called
procedure would work across the entire database, right?  
 
A simple *ADD trigger program, attachable to any file, and you never have to
deal with it in a program again.  It'd be an easy shop standard to implement
and adopt in one afternoon for all future enterprise development.
 
  
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Booth Martin   http://www.MartinVT.com
Booth@xxxxxxxxxxxx
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-------Original Message-------
 
From: RPG programming on the AS400 / iSeries
Date: Friday, March 28, 2003 13:10:30
To: RPG programming on the AS400 / iSeries
Subject: RE: "Reference #"
 
Booth wrote:
 
>If you want uniqueness just go for a random number. 
>The chances of a random number duplicating are slim, 
 
This is a subject near and dear to my heart. Apologies for the bandwidth...
I was once tasked with the mission of generating pseudorandom numbers to
pick employees for random drug testing. The hard part of the task was that
the employees had to be chosen at random. Provably so. So my random number
routine (S/38 days - no C API) had to generate stream of pseudorandom
numbers that was mathematically provable. So it could hold up in
court-provable. I used the October 1988 issue of Communications of the ACM,
article on random numbers authored by Stephen K Park and Keith W Miller as
the basis of my routine (which held up in court, as it turned out.)
 
The point is that "random" in this sense does not mean "no duplicates", but
it means that one cannot predict the next number in the sequence. It is
VERY likely that you will generate random numbers, depending on the universe
you are choosing from. Generally, people who know about the topic (not me!)
prefer the term "pseudorandom" because a given algorithm will generate the
same sequence of numbers given the same starting point in the sequence.
With a sequential number, one can readily predict the next number in the
sequence, but one can also be 100% certain there are no duplicates until you
run out of numbers in the universe (i.e. if you choose a two digit number,
you'll run out quickly!)
--buck