Ted Holt
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Guru: How To Override Query Options
May 21, 2018 Ted Holt
QAQQINI is a physical file with which you can control certain behaviors of the DB2 for i query engine. For a list of the query options that you can change, visit the IBM Knowledge Center. Normally you don’t have to use it, as the engineers of IBM have done a great job designing an optimizer that does a great job.
At times you may want to change a query attribute for a certain job. There is no need to build many QAQQINI files to handle all possibilities. Instead, you can temporarily override query attributes within a job. DB2 for …
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Guru: Odds And Ends
May 14, 2018 Ted Holt
Little things can make a big difference. Today I am pleased to present a few short tips that may make a difference for you. I hope you get something useful here. If you have short tips that you would like to share with your fellow readers, please email them to me and I’ll see what I can do. Have a wonderful day!
Hey, Ted:
I just read your article More Date And Time Conversions Using SQL. Just as aside, the scalar functions Decimal/Dec, Integer, and BigInt can convert times, dates and timestamps directly into a numeric representation in the …
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Guru: Refactoring into Routines
May 7, 2018 Ted Holt
In RDi and Refactoring, I illustrated the process of refactoring by taking code of a very old style and converting it little by little into something modern. I promised to write more about the subject, and today I fulfill that promise.
The things I did in that first article — removing indicators, removing the COMP op code, removing GOTO, and renaming variables — are great, but they are not the only refactoring techniques. One of the best ways to refactor is to create new routines or improve existing routines, especially routines that can stand alone.
To illustrate, I’ll begin …
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Guru Odds and Ends: Readers Respond
April 30, 2018 Ted Holt
I appreciate the comments and feedback that readers have contributed. Some of you sent it my way via the Contact page at IT Jungle. Others emailed me directly. Yet others left comments at the end of the articles themselves. I am always grateful for your knowledge and wisdom, however I receive it.
Knowing that you are very busy and don’t have time to revisit the articles we have published, I’ve collected some of that feedback for your edification. Please feel free to add to the body of knowledge.
Had to chuckle when I read Sorting Options For CPYTOIMPF, …
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Guru: RDi and Refactoring
April 16, 2018 Ted Holt
When I first heard the term refactoring, I thought, “So that’s what they call it.” I had been refactoring for years, my only tools being SEU and a compiler listing. I learned a long time ago that refactoring is often necessary to enhance code, especially poorly written code. Another reason I often refactor is to better understand poor code.
To refactor means to rewrite source code without changing its external behavior. Due to all the “legacy” source code (RPG II, RPG III, fixed-form RPG IV, OCL, etc.) in IBM i shops, the ability to refactor source code is a …
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Guru: LTRIM + RTRIM > TRIM
April 2, 2018 Ted Holt
When IBM enhances SQL for my favorite database management system, I feel so happy I could dance like Karlos Klaumannsmoller selling diabetes medicine. It is my pleasure today to let you know (in case you don’t already know) that IBM has once again enhanced two SQL functions to make them as powerful as their RPG counterparts.
The functions to which I refer are LTRIM (left trim) and RTRIM (right trim). Until recently these functions could only remove blanks (or hexadecimal zeros, for some data types) from the beginning (left) or end (right) of a string. IBM recently added …
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Guru: More Date And Time Conversions Using SQL
March 26, 2018 Ted Holt
Since many, if not most, IBM i shops store dates and times in numeric and character fields, it behooves those of us who program those systems to understand all available date- and time-conversion tools. A conversation with a fellow attendee of the recent RPG & DB2 Summit made me realize that I had not written about certain SQL conversion methods.
IBM i programmers need to convert date, time, and timestamp data from one format to another for at least two reasons. First, we can’t do date and time arithmetic with numeric and character fields. Second, the people whom we serve …
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Guru: Use SQL To Find Duplicate Source Code
March 12, 2018 Ted Holt
According to Brian Tracy, “good habits are hard to develop but easy to live with; bad habits are easy to develop but hard to live with. The habits you have and the habits that have you will determine almost everything you achieve or fail to achieve.” This is as true in programming as in anything else we may do.
Unfortunately, even those of us who strive for good work habits often have to follow the work of people who did not. One bad habit I come across occasionally is known in software engineering as WET solutions. WET stands for “write …
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Guru: Combine Related Rows Using SQL
February 12, 2018 Ted Holt
A reader writes: “Hey, Ted. In our ERP system, certain business objects, such as sales orders and purchase orders, can have multiple comment records. Is it possible, using SQL, to combine all the comment records for an order into one long comment and retrieve it as a column in a result set?”
I can relate to this. I can remember supporting an ERP system where not only the orders, but the order detail lines, could have such comments. End users depend heavily on such unstructured data to do their jobs. To answer your question, yes, it is possible and it …
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Guru: Three Suboptimal I/O Practices
February 5, 2018 Ted Holt
I have on numerous occasions looked at source code that I had written in previous years and asked myself, “Why on earth did I do that? What could I have been thinking?” We live and learn, or at least we hope we learn. Today I share three database practices that I see from time to time that can be simplified. Maybe there’s something for you to learn today.
Before I share the three examples, let me say that I do not consider the more cumbersome code to be wrong. To my way of thinking, any code that produces the correct …
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