Paul Tuohy
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Guru: Change XML Elements in SQL
February 18, 2019 Paul Tuohy
Over the last few years, it has become more common to store XML or JSON in a column in a table. Whereas SQL provides all the necessary functions to construct/deconstruct XML or JSON from/to relational data, it does not provide an easy means to change the contents of an element. In this article, I am going to demonstrate a technique for changing the contents of an XML element using an SQL stored procedure.
Just to provide some background, I was recently working on a project where DB2 XML Extender functionality was being replaced with the standard XML functions. The project …
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Guru Classic: Triggers – Allow Repeated Change
February 13, 2019 Paul Tuohy
Author’s Note: This article was originally published in November 2013. This has always been one of my favorite techniques for data modernization. I only wish I had thought of it back in the days of Y2K! The content of the article has been updated for free form RPG and some of the coding enhancements that have been introduced into RPG since 2013.
Recently, during a modernization project, I have been making use of the Allow Repeated Change (ALWREPCHG) option with before triggers. ALWREPCHG allows a before trigger to make changes to the record being inserted or updated, and that lets …
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Guru Classic: Call Again And Again And Again . . .
January 16, 2019 Paul Tuohy
Author’s Note: This article was originally published in October 2011 and recently came to mind when I had a discussion with a programmer bemoaning the fact that he could not (so he thought) have a recursive process in RPG. The content of the article has been updated for free form RPG and some of the coding enhancements that have been introduced, into RPG, since 2009.
In programming terms, recursion is the process whereby a function may call itself. Traditionally, this is something we are not used to in RPG. Programs and subroutines cannot call themselves. Or if you did somehow …
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Guru: Phonetic Functions In SQL, Part 1
September 17, 2018 Paul Tuohy
In my next two articles I am going to discuss the use of phonetic functions in SQL. You can use phonetic functions to select or order rows based on the phonetic sound of a string as opposed to the actual characters in the string. The obvious use of phonetic functions is with names, but they can be used with any string columns.
I must admit that this touches on one of my pet peeves — the spelling of my surname. I have lost count of the number of times I have had to spell my name two, three, or four …
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Guru: Handling Constraint Violations In RPG
September 5, 2018 Paul Tuohy
Author’s Note: The contents of this article were originally published as two separate articles – Handling Constraint Violations in RPG and Handling Constraints Revisited. The content of the article has been updated for free form RPG and some of the coding enhancements that have been introduced, into RPG, since 2009.
Constraints have been around for a long time but apparently have not quite made it into every programmer’s tool kit. This is partly explained by the fact that implementing constraints in an existing application can be tricky, but it doesn’t explain why constraints are not used extensively in new …
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Guru: Getting the Message, Part 2
August 29, 2018 Paul Tuohy
Author’s Note: This article was originally published in October 2009. Since then, I have worked on many modernization projects with many clients and, in every one of those projects, we have used some form of the contents of this (and the following) article. The content of the article has been updated for free-form RPG and some of the coding enhancements that have been introduced, into RPG, since 2009. The original articles also showed examples of direct calls to RPG subprocedures from PHP. Given that we now have many languages (Node.js, Python etc.) that interact with RPG, I changed the mechanism …
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Guru: Getting The Message, Part 1
August 1, 2018 Paul Tuohy
Author’s Note: This article was originally published in October 2009. Since then I have worked on many modernization projects with many clients and, in every one of those projects, we have used some form of the contents of this (and the following) article. The content of the article has been updated for free form RPG and some of the coding enhancements that have been introduced, into RPG, since the original publication of this piece.
When we look at modernizing applications (or writing new applications) one of the basic principles is to tier the application — i.e., separate the interface — …
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Guru: Beyond The Basics Of Code Conversion
March 19, 2018 Paul Tuohy
Today many RPG programmers are tasked with having to modernize existing programs. These programs often have long and varied history. They may be RPG IV programs or they may be RPG IV programs that were originally RPG II or RPG III programs, or any permutation or combination you can imagine. There are tools available to help us convert from fixed-form RPG to free-form RPG and, within RDi, we have options to help us reformat code and refactor variable names. But these tools can only go so far. We finally reach the point where we have to put fingers to the …
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Guru: A Handy Function for Unit Testing
December 4, 2017 Paul Tuohy
I would like to share a technique I use for dealing with lists in an RPG unit test program. According to Wikipedia, “. . . unit testing is a software testing method by which individual units of source code, sets of one or more computer program modules together with associated control data, usage procedures, and operating procedures, are tested to determine whether they are fit for use.”
In the world of modern RPG, this translates to writing “test” programs to test a specific piece of code. For example, when I write a subprocedure, I will write a test program that …
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