Friday, December 28, 2018

RPG400 manuals found

In my previous post I stated that IBM had removed the RPG400 user's guide and reference from the KnowledgeCenter.

Having performed a good deal of searching of the internet I have been able to find copies of both of these manuals in a dark corner of the IBM website. The manuals are from 2000. That may seem a long time ago for a "current" manual, but RPG3 has not been enhanced since RPG4 was introduced 23 years ago.

I have uploaded both of these PDF files to my Dropbox account, and you can reach them by using the following links:

Having given you these links I trust you will only refer to these manuals to remind yourself of some of the anachronisms of old RPG, rather than use to develop new code.

Thursday, December 27, 2018

RPG400 manuals no longer available

rpgiii manuals no longer on ibm website

As I have said in previous posts if you are programming only in RPG400, or RPG3, and not learning and using the latest version of RPG you are risking your future.

I found further proof yesterday browsing IBM's KnowledgeCenter looking for the latest RPG reference manual, when I noticed that the RPG400 (RPG3) manuals are no longer offered on line.

The following manuals are not included in the IBM i Information Center...

  • RPG/400 Reference...
  • RPG/400 User's Guide...

Wednesday, December 26, 2018

Searching strings using SQL

searching strings using sql locate_in_string

In a previous post I had written about using regular expressions to search for data within a string, but I did not mention the easier to use LOCATE_IN_STRING SQL scalar function. I believe this was introduced as part of IBM i Technical Refresh 2 for 7.3 and TR6 for 7.2.

The LOCATE_IN_STRING has four parameters:

  1. The source string to be searched (mandatory)
  2. The string used to search (mandatory)
  3. Starting position (optional)
  4. Instance, which number occurrence to find (optional)

I created a SQL DDL table, which I called TESTFILE, which I will be using in these examples. It contains one column, called DESCRIPTION, that is 40 long character, and the table contains just one row:

Wednesday, December 19, 2018

Using position to in a data structure array

using sflrcdnbr as position to in ds


This is a better way to sort a data structure array using an update to the SORTA operation code.



Any of you who have followed this blog for any amount of time are aware that I am proponent of using multiple row fetches in SQL to load data into a data structure array, which I will then use to load something like a subfile. In all the examples I have given in the past have been for files/tables that could contain many records/rows more than could be loaded into a load all subfile.

The slowest part of any program is loading data from the file/table. Using a multiple row fetch makes this many times faster by reducing the number of disk I/O to get my desired amount of data, versus getting one record at a time as I would need to do if I was using RPG to read the file/table. Every time I reload the subfile it is slow as I have to get the data from disk. This is especially true if I have a "Position to" field on my display file. If I am using a large file I have to reload the subfile every time the position to field is changed.

Wednesday, December 12, 2018

Using a trigger to prevent the deleting of records

trigger to block delete of record in file

The idea for this post came from a question I was asked about ways to stop a programmer from deleting records from a file using the STRSQL command. I thought this would be a good reason to use a combination of two solutions I have written about before.

My first thought was to use a validation trigger. Validation triggers must be executed before the insert, update, or delete occurs. That way I can determine if the STRSQL program was used, and if it was return an error code to the calling program.

Validation programs can be written in any language, and I have written them in both RPG and SQL. In this scenario I will be writing the trigger in SQL as, in my opinion, it is easier to write and, more importantly, easier for someone else to understand what is going on.

Wednesday, December 5, 2018

Find String PDM to an outfile

fndstrpdm to an output file

We have all had those requests from our superiors: "Where is insert-name-here file used?"

There are tools from third parties that will give me this information. I have used some of them, and found that they missed some objects. I always combine the information these tools provide me with a scan of the members in the source files in the production library list. I use the Find String PDM command, FNDSTRPDM, to search for the string of information I want. Most people who use this command use it to produce a printed list of the source members it finds. While that may be OK if there are just a few libraries and source members, I work in an environment where there are 25 libraries in the production library list and many of these libraries contain multiple source files. I do not want to have to copy information from all of the generated spool files into a physical file that I can share with others, that would be too much work.

Looking at the help for the FNDSTRPDM I had a eureka moment, that would give me a way to write the name of the source member to an output file.

Wednesday, November 28, 2018

Using CL to get records from a file for display

using cl to chain records from file

I have been receiving a lot of messages asking for more examples using the CL programming language. For those of you who have been asking I hope you find this useful.

A few weeks ago I received a request for help from a reader, just a beginner in the IBM i world, with an assignment he had to accomplish just using CL. He needed to write a program, or programs, that would allow the entry an employee id, and the program would retrieve information from the employee file and pass it to the display file for display. For anyone with a little RPG experience this is a very simple task, and we could all write a RPG program to do this in a few minutes. Many IBM i programmers balk to do anything like this in CL, but programming is programming, and the same steps you would perform in RPG can be duplicated in CL.

Wednesday, November 21, 2018

Using command to zip and unzip files

zipping and unzipping data to the ifs

In the past I have written about zipping files in the IFS using Java jar and APIs, this week a colleague showed me a simpler way to do it using a couple of IBM i commands.

He explained that these commands had been introduced in IBM i 7.2, and can zip and unzip files in the IFS as well as files in, what I call, the native IBM i environment. With these commands the zipped/compressed files are called "archive files", therefore, IBM named them:


Wednesday, November 14, 2018

Converting spool file data into data file

copy spool file data to physical file

I was surprised that I was asked this question, but as I have been asked six times in the last week it must be something that is important for people to find an answer for. Copying data from a spool file to a data file with separate fields is not an efficient way to get data. If you are considering using this method for capturing system information, spool files, active job info, etc, then you should be using the Views, Tables, etc that IBM has been creating for us to use. You can search this web site to see if I have written about getting to the information you desire using SQL. Trust me it is easier that what I am describing below.

In this example I am going to use the Work Output Queue command, WRKOUTQ, to generate a list of spool files, and I will be writing that data to a file. If I was doing this in the real world I would using the SQL and the method described in Output queue entries information via SQL. Now I have vented my feelings on this, let me proceed.

I want to know the following information about spool files in the QEZJOBLOG output queue:

Wednesday, November 7, 2018

Using new SQL built in function to convert character to number

using sql built in funtion to_number decfloat_format to convert alphanumeric number to decimal number

Included in the technical refreshes for IBM i 7.3 TR5 and 7.2 TR9 was a new Db2 for i built in function to convert character strings into numbers.

Why is this needed when I can just CAST the one type of a column to another?

02         CAST(COLUMN1 AS DECIMAL(10,2))

Numbers are problematic as I can make character representations of them in many different ways. I created a few examples of character representations of numbers, and then used the above SQL statement to display them.

Wednesday, October 31, 2018

Easiest way to search job descriptions

easy way to get information from job description using sql view

I have written about getting the library list from a job description using the QWDRJOBD API. An API is fine for doing things for one job description, but when I want to search all job descriptions that, for example, contain a library in their library list it is not easy to do with an API. A SQL view would be ideal for this.

IBM has come to rescue and I can now retrieve data from job descriptions using the SQL view JOB_DESCRIPTION_INFO. It is listed as one of the enhancements added with the latest round of IBM i Technical Refreshes, 7.3 TR5 and 7.2 TR9, but I have found it on a instance of IBM i that has not had the latest TR applied.

The view contains every column you need to know about a job description. I am not going to list them in this post, as I want to show examples of the kinds of information I have been asked from get from job descriptions in the past. If you want to see all the columns that are available there is a link at the bottom of this post to the IBM KnowledgeCenter page describing this view.

Wednesday, October 24, 2018

Extracting parts of date and time using a SQL function

enhanced extract for getting information from dates, times, timestamps

Another of the enhancements with the latest round of Technical Refreshes, TR5 for IBM i 7.3 and TR9 for 7.2, is to the Db2 for i Extract function. This function will retrieve parts of dates and times from date, time, and timestamp variables. Prior to these TRs I could extract just basic information from the date (year, month, day) or time (hour, minute, second).

The enhancements allows me to retrieve a whole lot more information than I will ever need to know about a date or time.

Let me start with a SQL DDL table I built to contain the data for my examples:

Wednesday, October 17, 2018

SQL NOW and playing with timestamps

using sql to get the timestamp

This post started off as one thing and quickly morphed into something more. I was going through all of the additions and changes in the new Technical Refreshes for IBM i 7.3 and started playing with the Db2 for i (SQL) NOW built in function.

NOW returns the current timestamp, and it has been around since at least 7.1. The latest TR allows me to give the decimal precision (fraction) of the seconds, for an example see below.


As I said now I can give NOW the decimal precision I want from zero to twelve.

Wednesday, October 10, 2018

Removing multiple alpha characters using SQL

using sql translate function to translate characters

I needed to remove alphabetic characters (A - Z) from a field in a file, and left justify the remaining numeric characters. These alpha characters could be before and/or after any numbers contained within the string. As usual I need data in a test file, TESTFILE, that I can play with to find a way to do what I want.

In these examples, as the subject I have only bothered with two records/rows in my table/file. Why have more when I know what works in these examples will work in any scenario.


The problem is that I want to replace any alpha character, no matter where in the string and what order they come in.

Wednesday, October 3, 2018

Creating uniqueness using rowid

rowid column in sql table to ensure record uniqueness

The Db2 for i manual offers using a row id column, ROWID, as an alternative to an Identity column for ensuring table row uniqueness. While I wrote about using a ROWID SQL data type in RPG, I did not describe how the ROWID works when defined as a column in a table.

ROWID can only be used in SQL DDL tables, I cannot add it to a DDS file, using ALTER TABLE. It is defined in a similar manner to an Identity column where I say that the columns contents are generated by Db2 for i automatically.

For example, here is the DDL table I will be using:

03   COLUMN2 CHAR(10),
05  )

Wednesday, September 26, 2018

SQL type variables in RPG

sqltype variables used when dcl-s in rpg

I have written about defining RPG variables defined as SQL types in past posts, which made me curious about all there are. Having searched in IBM's Knowledge Center I was disappointed to find that there was no one page with all of this information upon. Which gave me idea to write this, a list of all SQL types available.

If I am defining variables as SQL types my source needs to be compiled as a SQLRPGLE, as the RPG SQL precompiler converts these SQL data types into more familiar RPG equivalents.

The syntax for these variable definitions is simple, it is just:

Thursday, September 20, 2018

Closing all the files with one operation in RPG

closing multiple files with one rpg close operation code

There are times I stumble across things in the IBM manuals I felt I should have known. One of these is the ability to close all the files in a program with just one close statement. I have no idea how old this ability is, but it is relevant if you are programming your RPG in a modern manner.

Before main procedures were introduced to the RPG world, our programs were simple. We defined our files, and knew that they would close when the program ended.

01  **free
02  ctl-opt option(*nodebugio:*srcstmt:*nounref) ;

03  dcl-f PFILE1 ;
04  dcl-f DSPFILE workstn ;
05  dcl-f PRTFILE printer ;

06  *inlr = *on ;

Wednesday, September 19, 2018

Getting data for my auditors is simple using SQL

easy way to get user info using sql

It is that time of the year when the auditors start asking me for system information about the IBM i I am responsible for. The reports they want from me today are:

  1. Users who have not signed onto the IBM i for over a year.
  2. Users who have a user profile, but have never signed onto the IBM i.

It is also a good opportunity to show how some of the things I have written about in the past come together to make my job a lot easier.

A colleague, who is responsible for a different IBM i partition, asked me if there was an easy way to get this information?

Tuesday, September 18, 2018

Get a specific number row using SQL

getting the 98th row from a file using sql

This is going to be a quickie. I was asked:

How can I get the 98th record from a file using SQL?

Fortunately this very simple, but first let me go through setting up my example.

I created a Db2 for i table to use in this example. I could have used a DDS file just as well. But this gives me an excuse to use one of what I consider one of the cool features of Db2 for i tables, identity columns.

If I am using a table with an identity column I don't have to increment some value in a field to keep a unique field in a file or table. The value for an identity columns are auto generated by Db2 for i, so all I have to do is just define them in my table. My example table just contains an identity column.

Friday, September 14, 2018

IBM i 7.3 TR5 and 7.2 TR9 now released

ibm i 7.3 tr5 7.2 tr9 out now

Today is an exciting day as the latest Technical Refreshes for the currently supported releases of the IBM i are available to download as PTFs:

  • IBM i 7.3 TR5
  • IBM i 7.2 TR9

I am not going to repeat what these TRs include, I am going to give you a]the link to the post I wrote when they were announced in August, see IBM i 7.3 TR5 and 7.2 TR9 announced.

The PTFs you will need to download and apply to install the new TR on your IBM i are:

Wednesday, September 12, 2018

Generic program to use SQL count for any file

program to get count of records from any file using sql

The germ for this post came from a question I found in an IBM i Facebook group. How could this person write a program where he would pass the name of any file to SQL and get a count of records in that file. I gave my answer to that question, but the more I pondered I came up with what I consider to be a better solution. Which is what I am going to describe in this post.

I have written about creating and executing SQL statements contained in program variables before, and this just builds upon that.

Fortunately the SQL syntax to count the number of records is the same no matter what file or table I use:

SELECT COUNT(*) FROM some_table
 WHERE some_column(s) = some_value(s)

Wednesday, September 5, 2018

Using SQL to determine how many records end with...

determine what alpha fields end with

I was asked an intriguing question that I thought it would make a good post for this blog:

Using SQL, how would I get a count of all records in a file where the value in an alphanumeric field ends with 18?

Rather than show just the finished SQL statement I am going to show how, and why, I built each part of the select statement.

Let me start with my test file. It will come as no surprise to regular readers of this blog that it is called TESTFILE, and is in the library QTEMP. The file contains one alphanumeric/character field, CHARFIELD, its length is irrelevant. Its contents looks like:

Wednesday, August 29, 2018

Getting the System Name using SQL

get as400 system name using only sql

What appeared at first look to be a simple challenge given on Twitter:

How would you get the system name of a partition via a SQL statement?

In a CL program this is simple as I can retrieve the system name using the Retrieve Network Attributes command, RTVNETA.


So how to get the same information using SQL?

Wednesday, August 22, 2018

Using Environmental Variables

environment values are more than just widening the strdbg window

This all started with what was going to be a very short post about using an Environment Variable to set the width of your debug screen. But I became curious and by the time I finished playing with them this grew into how to create your own Environment Variables, and use them.

Let me start with the question: What is an Environment Variable?

Environment Variables come in two types:

  1. System – these Environment Variables are stored in the global environment space and are available to all jobs running on this IBM i system, and are persistent even when the system is IPL-ed.
  2. Job – the variables are outside the program's space, and are job specific, when the job ends they are automatically deleted.

Wednesday, August 15, 2018

Getting data from XML file directly into data structure array

xml straight into file

I have written before about retrieving data from a XML file in the IFS. In that example I took that data from the file into a XML column in a DDL (SQL) table and then processed it from there. Since I published the example I have received two messages, one from Birgitta Hauser and another from Jan Koefoed-Nielsen, giving me examples of how to retrieve the data from the file and format it into columns, not using a DDL table as an interim step.

In this example I will not be directly outputting the information from the IFS XML file directly into an output file or table in IBM i. My experience of receiving XML files makes me want to validate what I am sent, before I start updating production files. A comma in a number, currency symbols, characters in what should be numeric value, and untranslatable characters should all be handled before updating any file. To this end I will be retrieving the data from the XML file and putting it into a data structure array. I can then "read" the array and perform any validations I want.

Monday, August 13, 2018

AS400 to IBM i: And we're just getting started

Video featuring Steve Will, chief architect of IBM i, and Alison Butterill, product offering manager for IBM i, showing ways IBM i clients have innovated over the past 30 years.

Runs just over 1 hour.

Hosted by HelpSystems, recorded July 18, 2018.

Wednesday, August 8, 2018

Using reference fields

using reference fields in dds, rpg, sql

When I first started programming on the AS400 the biggest improvement I encountered, compared to the System/36, was the external database. No longer did I have to have file specifications in my RPG programs, and I now had the ability to define fields by referencing another. Over the years I have used the referencing ability whenever I can had to define fields in files or variables in my RPG programs. By using reference fields makes database changes easier as a field's definition is changed in one place, then by recompiling all of the objects with the referencing, the new objects all have the new definition of the field in them.

In the past fortnight I have been asked several times about using reference fields, and in my experience there are many more who would like to ask the same question but feel intimated to do so. Therefore, I am writing this post to give examples of how I use them and why I do things the way I do.

All well-built databases have a data dictionary that defines the types of all the fields, or columns, within it. On AS400 and IBM i many of us achieved something similar using a reference file. This file contains the definition of every type of field that could be contained in any of the other files in the application.

Tuesday, August 7, 2018

IBM i 7.3 TR5 and 7.2 TR9 announced

ibmi 7.3 tr5 7.2 tr9 announced

The awaited announcement of new Technical Refreshes for IBM i 7.3, TR5, and 7.2, TR9, has been made. So what's new?

On the hardware side is the announcement of the Power9 chip based IBM Power E980 model 9080-M9S server.

I am not going to list all the changes on the software side just those that catch my eye at first glance.

Wednesday, August 1, 2018

Copying any data to and from a file in the IFS

using sql to write to a text ifs file

In previous posts I have shown how to write SQL data to a file in the IFS and then how to retrieve the XML data from an IFS file, but what about just plain old text?

In this post I am going to keep the example as simple as possible so that you can see how easy this is. I am going to write three strings of data, "records", to an IFS file, retrieve the data from the file, then move each the "record" into an array. Some of what I am describing here I have also mentioned in my earlier posts, but I think it is valuable to have it in here too.

My example program is only 32 lines, which goes to show easy this is. All the hard work is performed by Db2 for i.

Wednesday, July 25, 2018

Using SQL UDF with RPG

using values from sql udf in rpg program

This short post comes from a discussion I was having with two other IBM i developers at my place of work. I had shown them a number of SQL User Defined Functions, UDF, I had created to make my SQL statements easier.

"That's fine," started one of the developers, "but how does that help me in RPG. Won't I have to duplicate the procedures so I can call them in RPG?"

"No", I replied, "you can call them using SQL".

At first they were skeptical. Having shown them how easy it was to do they were sold.

Wednesday, July 18, 2018

Getting data from a XML file using SQL

retrieve xml data from file in ifs

A couple of months ago I write a post about creating XML from an IBM i hosted file and write it to a file in the IFS. It was obvious to me that I would have to write this post, describing how to get data from the XML file using SQL.

I could extract the data from the XML file in the IFS using the RPG operation code XML-INTO, but I want to use SQL to do this.

Where to start? I guess with the XML data. The XML file, xmlfile.xml, is in my folder, MyFolder, in the IFS. It contains the same data I used in the post about writing to the XML file. In the file the data is not formatted, it is just one long string of data.

Wednesday, July 11, 2018

Using an output queue to send spool files to another partition

create remote outq to another as400

The germ of the idea for this post came from a conversation I was having with two other programmers I work with. The conversation became finding an easy way to transfer spool files from a development IBM i partition to a production partition.

Where I work there are multiple partitions on one PowerSystems server. These partitions are used by various subsidiary companies in different parts of the USA, and three locations in Europe. If a modification is made to a spool file layout, for example: invoice, how do I show a user in Germany or Illinois what this new layout looks like when I am in California? The development partition does not connect to all the printers used, as we do not want test data printing on a "live" printer when testing. In my experience if I copy the spool file to a PDF the user is not convinced. The only way they will be convinced that the change works is for it to print on their printer.

Wednesday, July 4, 2018

Securing DDM files

making ddm file connections secure

Using DDM files is a very easy way to access data from another IBM i. I frequently use them to pass data from one IBM i partition to another and back.

All I need to do is to create the DDM file with the following command and be able to access the data in the file SOMEFILE in the library SOMEIB in the IBM i partition RMTSYS.

                            Create DDM File (CRTDDMF)

Type choices, press Enter.

DDM file . . . . . . > DDMFILE  
  Library  . . . . . >   QTEMP     
Remote file:
  File . . . . . . . > SOMEFILE  
    Library  . . . . >   SOMELIB   

Remote location:
  Name or address  . > RMTSYS                                  

Type . . . . . . . . . *SNA     *SNA, *IP

Wednesday, June 27, 2018

Different types of numbers in files and tables

different types of numbers that can be used when defining dds files and sql tables

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

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:

  1. Physical files
  2. Display files
  3. Printer files

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:


               RAND ( )

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:

Wednesday, May 2, 2018

Update the current row when using cursor

updating current SQL cursor

I was asked how to update the current row if I am "reading" a file/table using a SQL cursor. At first this question took me aback, it was not that I did not know how to do it, but more a question of why?

What I consider to be one of the biggest benefits of using SQL to process (fetch, delete, and update) data from your database in sets, "chunks" of data. If I need to process a hundred rows/records of data why get each one individually? as that would be a hundred I/O operations. I can get all hundred rows in one I/O operation, thereby, reducing the amount of time and system resources needed to get the data.

I spent some time thinking of a scenario where I might want to fetch rows/records one at a time. I came up with the scenario of an interface. One program would add data to a file, and another would retrieve the data from the file and process the transaction. My example will be that second program.

Wednesday, April 25, 2018

Easy to create shortcut commands

creating your own shortcut commands

After my post about how to create your own commands I received messages from readers giving me examples of how they have created their own shortcut commands, to do the same as the standard IBM i command but shorter. In one example the command SP did the same as WRKSPLF.

I don't think many people know of proxy commands. These allow me to create shortcut commands of the regular IBM i commands without any programming. You can even make proxies of proxy commands, although I cannot think of a reason why I would ever think to do so.

In this example I am going to create a proxy command, SP, for the Work with Spooled Files command, WRKSPLF.

Wednesday, April 18, 2018

Sending your own program created messages to the error subfile

filling the error subfile, errsfl, with program generated message

I have previously written about using the error subfile to display error messages, rather than the message subfile. Personally I like using the error subfile as it is another case of allowing the operating system to do the work for me.

Since publishing that article I have received messages asking how can people create their own error message text, in the RPG program, that is displayed in the error subfile.

Fortunately there is a simple way to do this that will work in either RPG in CL.

No matter which language I use the display file can be the same. Here is the display file I will be using in this example.

Wednesday, April 11, 2018

Built in function to return name of procedure

%proc built in function to return procedure name

Until the last round of Technical Refreshes, IBM i 7.2 TR7 and 7.3 TR3, I could not find a way to retrieve the name of the procedure that I was in. The program data structure enticed me with the *PROC keyword. This was not the procedure's name, but rather either the program's or module's name.

01  DPgmDs           SDS                  qualified
02  D ProcName          *PROC

01  dcl-ds PgmDs psds qualified ;
02    ProcName *proc ;
03  end-ds ;

Fortunately these two Technical Refreshes introduced a new built in function, BiF, to returns the name of the current procedure: %PROC

This example is of what I call a closed subprocedure and how this new BiF works.

Wednesday, April 4, 2018

Handling nulls in CL

in a cl program how to handle a null value from a file

I have written previously about how to handle nulls values in RPG and in SQL, but until this week I had never had a problem with null in a CL program.

The CL program was "reading" a SQL table, where some columns/fields were null.

01 PO18087       P            145.67
02 PO18556       C             15.36
03 PO18223       -                  -
04 PO18777       D                  -

The CL program is simple.