• A Chicken-and-Egg Trigger Problem

  February 25, 2004 Hey, Ted

  Say I have two physical files: A and B. File A has an insert trigger program (written in RPG IV) that adds new records to B. That is, when someone adds a row to A, the trigger adds a row to B. What would happen if a program read B and added new rows to A?

  

  insert into A (TransID, AnotherValue, Amount)
    select (TransID, AnotherValue, (0 - Amount) from B
       where substr(TransID,1,1) = 'T'
  

  The intention is to zero-out the balances of all transaction IDs that begin with the letter T. That is, the sum of all records with a

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• OS/400 Alert: Security Starts At Home

  February 25, 2004 Shannon O'Donnell

  Everyone talks about security, but how many do anything about it? If you are looking for tools that will help you get a handle on the various security holes and vulnerabilities on your PC and AS/400, this issue of “OS/400 Alert” is for you. I’ll cover several tools that you can download and use to make your PC and AS/400 as secure as they can be.

  

  MICROSOFT BASELINE SECURITY ANALYZER

  Are you overwhelmed by the number of viruses and security holes spreading on the Web on a daily basis? Do you fear that you may not be able to keep

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• iSeries Navigator: A World of Wizards

  February 18, 2004 Shannon O'Donnell

  When learning to do something, whether programming on a computer or playing a song on the banjo, it is always easier when you have someone standing by to teach you all those little tricks and tips that make the task easier. When it is not possible to have such an expert on hand, the next best thing is to have a tool that can teach you. In iSeries Navigator, the experts are wizards.

  

  A wizard is a piece of software or a program that was written to guide users through completing a task, usually by using a straight-forward, logical sequence

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• A Super Way to Display a Date

  February 18, 2004 Hey, Ted

  Here’s a subprocedure I wrote that you might want to publish in your newsletter. My routine uses the ILE CEE APIs to format a date as day of week, month name, day, and year, like this:

  

  Wednesday, February 18, 2004
  

  I use the CEEDAYS API to convert a date to Lilian date format, which is the number of days elapsed since October 14, 1582. Then I use the CEEDATE API to format the Lilian date into a character string. In the case of an error (for example, a date before October 14, 1582), I return the ISO character representation of

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• Short Circuit Evaluation

  February 18, 2004 Hey, Ted

  Here’s a simplification of the code for subprocedure EqAnyNum, which you published on January 28. I was able to shorten the code because of a feature called short circuit evaluation, which is explained in chapter 21 of the V5R2 RPG IV reference.

  

  –Mel

  Thanks to Mel for bringing short circuit evaluation to my attention. Here’s Mel’s code.

  C/free                                    
       if %parms >= 2 and BaseVal = Val01 or
          %parms >= 3 and BaseVal = Val02 or
          %parms >= 4 and BaseVal = Val03 or
          %parms >= 5 and BaseVal = Val04 or
          %parms >= 6 and BaseVal = Val05 

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• OS/400 Alert: Creating a Private Subsystem

  February 18, 2004 Joe Hertvik

  By default, OS/400 comes with one interactive subsystem called QINTER, which is where all 5250 green-screen jobs run. For most scenarios, this is adequate, but many times you may want to segregate interactive work into different subsystems.

  

  For the purpose of security, you could limit the time of day or days that certain users can sign on. If you have consultants who are authorized to use your system only during working hours, you could segregate their workstations into their own private interactive subsystem and shut down that subsystem during off-hours.

  For maintenance purposes, you could create a separate subsystem for

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• OS/400 Alert: Virus Targets AIM

  February 18, 2004 Shannon O'Donnell

  Do you use the AOL Instant Messenger program to communicate with your friends and coworkers? If you do, you might become the recipient of a new virus that’s spread through the program. In this issue of “OS/400 Alert,” I’ll give you the lowdown on this sneaky new virus. I’ll also tell you about several other viruses and updates that you should be aware of.

  

  AIM BECOMES TARGET OF SNEAKY VIRUS

  If you use AOL Instant Messenger, you may become the target of new virus-like software attacking AIM users. I say virus-like because it is not truly a virus. Virus

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• What You Should Know About Activation Groups

  February 11, 2004 Joel Cochran

  In the last several articles we began dipping our toes into the ILE waters by learning about service programs, binder source, and binding directories. You should now have a firm grasp of these building blocks and be ready to start constructing an ILE application. But before plowing ahead, we need to examine the most frustrating and least understood aspect of ILE: activation groups.

  

  WHAT IS AN ACTIVATION GROUP?

  I like to think of an activation group as a container for memory and other resources. According to the ILE Concepts manual (PDF format), this container is considered a “substructure of

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• Soft-Coded Report Distribution

  February 11, 2004 Bruce Guetzkow

  [The code for this article is available for download.]

  

  Printer files let programmers separate one type of output from program processing. When a printer file is created, several attributes can be specified (like output queue, copies) to simplify report routing instructions. But over time things change. You may, for instance, need to send reports to a different output queue or change the number of copies. The typical response is to update the affected printer files, provided you have the authority. This article presents an alternative: soft-coded report distribution.

  Soft-coded report distribution lets you change printer file attributes

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• Dealing with Divided Date Fields

  February 11, 2004 Hey, Ted

  Some of our ancient database files have separate fields for year, month, and day parts of a date. Combining separate fields to form single date fields is manageable but messy. Building logical files to combine the fields is not always practical, although we have done some of that. When digging around on Google one day, I accidentally discovered an SQL function that is well-suited for divided date fields.

  

  The function I discovered is called DateSerial. It is a part of various software products, including Microsoft Access and various versions of Visual Basic. It requires three arguments: year, month, and day.

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