• Guru: Web Services, DATA-INTO and DATA-GEN, Part 1

  April 5, 2021 Jon Paris

  Many of the “Can you help me with. . . ” communications that cross my desk these days include reference to JSON. Sometimes the questioner is receiving JSON in a file, or has to retrieve it from a web service, or needs to generate JSON in response to a query. While there are many ways to handle these requirements, RPG’s built-in DATA-INTO and DATA-GEN can do a lot of the heavy lifting for you and are quite simple once you understand the basics.

  In this series of tips, I am going to start with a basic example that uses both …

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• Guru: Stub Testing And SQL

  March 29, 2021 Ted Holt

  A stub program is a program that does nothing but stand in as a place holder for a real program, which may or may not exist yet. I have used them for years to help me test program changes. There are also stub subroutines, stub subprocedures, etc. What I want to talk about today is how to use a similar concept for SQL queries.

  You can use your favorite search engine to learn about stubs, but I’ll give you an example to increase the chances that you’ll know what I’m talking about. Let’s say that I am modifying a CL …

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• Guru: Getting Yum And Bash Up And Running

  March 15, 2021 Rob McNelly

  In the March 1 edition of The Four Hundred, I noted that an emphasis on things like system/application modernization and open source solutions gives IBM i newcomers a degree of comfort with the platform. I also made the point that no matter how long you or I have been at this, there are always people, young or not so young, who are new to the platform and come to this site seeking introductory information about various tasks and capabilities.

  With this in mind, I want to delve further into open source for those who are new to it. As …

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• Guru: SELECT INTO And Arrays

  March 8, 2021 Ted Holt

  I got egg on my face again. I told a couple of colleagues that they could use the SELECT INTO statement to load multiple rows into an array data structure in an RPG program. Boy, was I wrong! I had confused SELECT INTO with the FETCH statement, of course, which retrieves data over which a cursor has been declared.

  But the matter continued to nag me. I much like the simplicity of SELECT INTO. There’s no cursor to declare, open, fetch from and close, the same reason I like the FOR loop in SQL PL. It seemed (and continues …

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• Guru: For IBM i Newcomers, An Access Client Solutions Primer

  March 1, 2021 Rob McNelly

  I enjoy reading about IBM i Fresh Faces. Sure, it’s refreshing to see that it’s not just graybeards like me who are working on the platform, but what really matters is that young people are learning about, getting hands-on with, and coming to love IBM i. I appreciate that many of these stories revolve around system/application modernization and open source solutions. This gives newcomers to IBM i a degree of comfort by reducing their learning curve.

  Learning any new technology is challenging. Specifically, how do you go from learning about the concepts to actually getting on a machine and …

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• Guru: Prompting Stored Procedures

  February 22, 2021 Paul Tuohy

  In this tip I would like to touch on two items, in relation to stored procedures, that may have escaped your notice: prompting stored procedures and/or parameters (in Run SQL Scripts) and passing parameters by name.

  I must admit that, as I have gotten older, my ability to remember the names and parameters for stored procedures has, shall we say, decreased. At this stage, I am lucky if I can remember which library/schema one of my stored procedures is in!

  A case in point. I recently received an e-mail about a stored procedure I had written about (back in 2015) …

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• Guru: When An Outer Join Is An Inner Join

  February 15, 2021 Ted Holt

  When is a boy not a boy? When he’s abed! When is a door not a door? When it’s ajar! When is an outer join not an outer join? (Sorry, no dad joke here. Three dad jokes in one paragraph would have been too many, don’t you agree?) Let me answer that last question.

  In my work I often see outer joins that are not really outer joins, but inner joins. Oh, based on what I’ve heard from IBM, the query engine may treat them as outer joins, but the result set is the same as that produced by an …

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• Guru: The Uncertainty of Redundant Row Selection

  February 8, 2021 Ted Holt

  Is redundancy good or bad? I say it depends. According to Nassim Nicholas Taleb, “Redundancy is ambiguous because it seems like a waste if nothing unusual happens. Except that something unusual happens — usually.” I have seen some unusual behavior when joining database tables, but try as I might, I can’t figure out what that unusual behavior depends on. Let me show you what I mean.

  First, we need some data for illustration. Let’s say that our company uses an ERP system that was designed for make-to-stock manufacturing. What the factory builds goes into the warehouse, and customer orders are …

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• Guru: A Philosophically Engineered Approach to the Processing of Parameters, Take Two

  February 1, 2021 Ted Holt

  A strange thing happened to me recently. I was writing a new program and like a good programmer, was not reinventing the wheel. I was calling a utility program that calculated the values I needed. However, this utility program, which had always worked correctly, was giving me invalid data. How is it possible that a program can work properly for a long time and suddenly go bad?

  The answer to this question was ably answered by Rick Cook, who wrote “Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying …

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• Guru: What’s Your RDi Preference?

  January 25, 2021 Susan Gantner

  To say that RDi is highly customizable is putting it mildly. There are hundreds of preferences to set as well as many other types of customizations that can be done. I’m often asked about my favorite preference settings and other customizations. This tip includes a few of the ways that my own workspace differs from the default “out of the box” RDi settings.

  In this tip I’ll concentrate on some of my favorite preference settings. In a later tip, I’ll continue the discussion on additional customizations I make in my RDi workspace using other methods besides the preferences dialogs.

  I’ll …

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