Thursday, June 21, 2018

30th anniversary of AS400 launch

30th anniversary of as400

There has been a lot of fanfare about this year being the 30th anniversary of the launch of the AS400, the esteemed ancestor of the IBM i operating system. Many others have written tomes about what this anniversary means to them, and I thought I would add a few thoughts of my own.

On June 21 1988 the server and operating system that had be known by insiders as Silverlake was launched to the world as the AS400. It was the brain child of Dr Frank Soltis to create a system for midsized businesses.

Wednesday, June 20, 2018

Different types of numbers in RPG

using different types of number fields in rpg

For those of you like me who have been programming in IBM i and its predecessors for some time this might seem a simple subject matter. But I have received quite a few questions regarding numbers in the past few weeks. So I thought I would write something answering those questions and a bit more about the different types of numbers you will find in IBM i.

The most basic types of numbers everyone who has programmed on an IBM i has used are packed and zoned numbers. Zoned numbers are not anything new they are just the name that is used for what we use to call signed numbers. What is the difference? Why would I want to use packed rather than zoned? It really comes down to space. Back when computer first started using disk storage it was very expensive, therefore, everyone tried to reduce the amount of disk space they use. Someone came up with the idea of "packing" numbers to reduce the amount of space they use. "Packing" is a method I can store two numbers in each byte. Rather than spend paragraphs explaining what this is I think an example, like a picture, paints a thousand words.

Wednesday, June 13, 2018

Using Built–in global variables

using sql built in global variables

I wrote about creating my own global variables in the past, but I failed to mention the "built-in" ones. A global variable is a SQL variable you can create, place a value into, and then use within the same session. This is a great way to pass SQL variables from one program or procedure to the next. When the SQL session ends the variables are return to their default. If I change a global variable in one job, it does not change the value in the global variable in another job.

What I failed to mention in that post is since IBM i 7.2 there are some "built-in" global values that contain system information, and are maintained by the operating system. This allows me to get the values from these global variables and use them in my own programs and procedures. These built-in global variables can be found in two libraries, SYSIBM and QSYS2, I have no idea why IBM decided to split them between the two.

As with the user created global variables they are all CLE service programs:

Sunday, June 10, 2018

Happy fifth birthday to RPGPGM.COM

Today marks the fifth anniversary of this blog. These five years have been an exciting time for IBM i, and I have been fortunate to have been able to write about many of the wonderful features and functions that have been added to this operating system. Over these years I have written over 450 posts, and if I had to select five of my most favorite things I have written about, and frequently use, they would be:

Wednesday, June 6, 2018

Creating a XML file in just one step using SQL

writing xml directly from sql to ifs file

When I published the post about creating a XML file using SQL I received a message from Birgitta Hauser making a suggestion:

When using RPG Variables defined as SQLTYPE(CLOB: Length) the maximum supported length is 16 MB (RPG Limit) But there is no need to use RPG functions. Instead of writing the data into a variable first, It can be directly written into the XML-File in the VALUES ... INTO Statement.

She makes a very valid point. Many of my example programs have extra steps in them so that you, the reader, can see interim results. I feel this is a good thing as it helps to understand the processes shown.

Wednesday, May 30, 2018

Generating random numbers using SQL

generate random numbers using sql

In the past I have written about generating pseudo-random numbers using APIs, CEERAN0 and C's rand. But I always return to using SQL to generate the random numbers for me. I think it is because it is so simple to use.

In its simplest form if I want one pseudo-random number I can just use the following statement:

SELECT RAND() FROM SYSIBM.SYSDUMMY1

               RAND ( )
5.3215124973296302E-001

Wednesday, May 23, 2018

How to SQL table's long names in RPG program

using long column names from sql table

The seed for this post came from a conversation I had with one of my work colleagues. He complained that even though he could give the columns (fields) in a DDL (SQL) tables names longer than ten characters he found that it was hard to use these names in programs, especially those using printer or display files.

He is not the first person who had made this observation to me. Over the time I have written this web site others have made the same observation.

Let me show what I shared with him so that he could easily overcome this perceived shortcoming.

Monday, May 21, 2018

New Technical Refreshes coming in September?

While poking around in IBM's developerWorks wiki I noticed that pages for the next Technical Refreshes for IBM i 7.3 and 7.2 have already been added.

Wednesday, May 16, 2018

Deleting the current row when using cursor

delete current sql cursor row

In a previous post I wrote about how to perform an update of the current row/record when using a SQL cursor in a RPG program. I have been asked what could be considered the obvious follow on question: How I delete the current row/record when using a SQL cursor?

Fortunately it is as simple as the Update process. All I need to do is...

  • Define the cursor
  • Open the cursor
  • Fetch from the cursor
  • Delete
  • Close the cursor

In its simplest form a program could just be like this:

Wednesday, May 9, 2018

Creating a XML file

create xml file using sql and rpg

In an earlier post I described how to retrieve information from a XML file. This left me thinking how do I create a XML file just using native IBM i functionality?

I wanted to keep my program simple, K.I.S.S. After a good deal of research I have an example program of 28 lines, which takes data from a DDS file or DDL table, converts the data to XML, and outputs the data to a file in the IFS. I need acknowledge Birgitta Hauser here. She is someone whose work I study, and articles I always read. Some of the code in this example is based upon a series of example procedures and programs she posted on Github. I will post a link to her Github at the bottom of this post along with the other reference links.

Before I continue I want to describe the parts of a XML document so you understand when I call an element something what it is. Below is an example of a XML document: