In a previous post I wrote about the different types of numbers that could be used in RPG. Alas, we have been spoiled with RPG as there are less types to choose from in when defining numbers fields in DDS files and columns (SQL) DDL tables.
DDS files come in different forms, and they all have their own rules as to the types of numbers are valid. I am only going cover the major types, which in my opinion are:
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.
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.
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:
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:
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.