Wed, May
2 New Articles

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL

  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

SQL views provide alternative ways of accessing the data in a table.

Editor's Note: This article is excerpted from chapter 3 of Programming in ILE RPG, Fifth Edition.

 Although a program can retrieve and process virtual rows from a view, the view does not actually contain data. Instead, it stores an access path, a sequence of pointers to the actual data in one or more tables. When SQL creates a new view, the database constructs an unkeyed logical file based on a physical file. An RPG program does not make a distinction between a table and a view when it is processing the file—the program can read and generally update the file whether it is a table or a view.

The most common uses for a view are to select certain rows (a subset) from a table, select a subset of columns from a table, or select a combination of both functions. The SQL Create View statement produces a view. The access path is built from an SQL Select statement integrated within the Create View statement:

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 1


Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 2


Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 3

These Create View statements contain three major clauses: 1) the name of the view, 2) a Select statement—more accurately called a fullselect—to designate the rows and columns to be in the view, and 3) the name of the view’s record format.

A fullselect is a component of the Create View statement. It specifies the rows and columns from one or more tables that make up the view. The fullselect names the columns to retrieve, the table from which to retrieve them, and optionally a Where clause to specify criteria for row selection.

In the following fullselect,

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 4

the view includes only those rows from the Customers table that represent male (Cgender = 'M') customers. The view has all the same columns as the original table (Select *). Although the Customers table contains all the possible rows, if a program processes this view instead, the view will have access only to male customers.

When the view is to have only certain columns from the table, the fullselect names those columns to use:

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 5

In this example, the fullselect specifies only four columns from the table to include in the view. Every row from the table is also in the view because the fullselect has no Where clause to filter out rows. You can, however, combine a column list and a Where clause in the same fullselect:

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 6

Note that you cannot sort a view, nor can the fullselect contain an SQL Order By clause.

Creating Indexes with SQL

An SQL index is a database object whose primary purpose is to improve the performance of SQL statements. An index does not contain data, and SQL cannot retrieve rows from an index. The IBM i database implements an index as a keyed logical file. As you might expect, the SQL Create Index statement creates an index:

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 7

This Create Index statement contains four major clauses: 1) the name of the index, 2) the name of the table on which to create the index, 3) a list of the key fields in the index, and 4) an optional record format name. The statement might also include a Where clause to cause the index to select only those rows that fulfill specific criteria:

Programming in ILE RPG - Creating and Using Files: Creating Views and Indexes with SQL - Figure 8

Although SQL does not retrieve data from an index, an ILE RPG program can declare the index in its file declarations, enabling it to read and write records in the Custidx logical file.

Next time: DDS Database Concepts.  Can't wait? Want to learn more about Programming in ILE RPG?  Pick up the book in the MC Bookstore today!

James Buck
Jim Buck's career in IT has spanned more than 35 years, primarily in the college education, manufacturing, and healthcare industries. Past president (13 years) of the Wisconsin Midrange Computer Professional Association, he has served on several teams developing IBM and COMMON certification tests. Jim has co-authored several IBM i textbooks with Bryan Meyers that are used by many companies and in colleges worldwide. Other accomplishments include: recipient of the 2007 IBM System i Innovation - Education Excellence Award, 2014 COMMON President's Award, and 2013/2016/2017 IBM Champion - Power Systems.

Jim is the president and founder of imPower Technologies, where he provides professional IBM i training and consulting services. He is active in the IBM i community, working to help companies train their employees in the latest IBM technologies and develop the next generation of IBM i professionals.

MC Press books written by Jim Buck available now on the MC Press Bookstore.

Control Language Programming for IBM i Control Language Programming for IBM i
Master the A-Z of CL, including features such as structured programming, file processing enhancements, and ILE.
List Price $79.95

Now On Sale

Mastering IBM i Mastering IBM i
Get the must-have guide to the tools and concepts needed to work with today's IBM i.
List Price $85.95

Now On Sale

Programming in ILE RPG Programming in ILE RPG
Get the definitive guide to the RPG programming language.
List Price $95.95

Now On Sale

Programming in RPG IV Programming in RPG IV
Understand the essentials of business programming using RPG IV.
List Price $79.95

Now On Sale



Support MC Press Online

$0.00 Raised:

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: