IBM i LEARNING LIBRARY

AS400 and IBM i tutorials

Find a practical guide for the task in front of you: learn RPGLE, read and update files, query Db2 for i, manage batch jobs, or diagnose an error. Each path connects explanations and examples to official IBM documentation and related practice questions.

New to the platform? Start with IBM i foundations. These tutorials cover concepts often searched as AS400, AS/400 or iSeries development, with release-specific details identified in the IBM references.

Learn step by step

AS400 / IBM i Basics: Libraries, Objects, QTEMP and IFS

Learn AS400 and IBM i basics with practical examples of objects, library lists, QTEMP, source members and IFS paths, plus a first troubleshooting checklist.

Easy · 7 sections IBM i Files Tutorial: PF, LF, DDS, CHAIN and READE

Learn IBM i physical and logical files, members, keys and RPG file operations through practical examples, level-check diagnosis and SQL comparisons.

Easy · 7 sections Db2 for i SQL Tutorial: Joins, CTEs, NULLs and Updates

Practise Db2 for i SQL joins, NULL handling, common table expressions and guarded updates with worked results, RPGLE host variables and IBM references.

Intermediate · 7 sections RPGLE Tutorial: Variables, Arrays, Dates and Procedures

Learn RPGLE variables, decimal calculations, arrays, date validation and procedure parameters with fixed-format and fully free examples and test cases.

Intermediate · 7 sections IBM i Batch Jobs: SBMJOB, Job Queues, CL and Job Logs

Troubleshoot IBM i batch jobs with SBMJOB, job queues, MSGW, job logs and CL examples. Learn to separate submission, execution and business completion.

Intermediate · 7 sections ILE RPGLE Guide: Service Programs, Binding and Activation

Build an ILE RPGLE service, understand module and binding-directory dependencies, preserve exported interfaces and troubleshoot activation-group state.

Advanced · 9 sections IBM i Data Queues and Data Areas: Examples and Recovery

Learn IBM i data queues, data areas and message queues with SQL and CL examples, timeout handling, duplicate detection and practical recovery scenarios.

Intermediate · 7 sections IBM i Troubleshooting: RPGLE Debug, Authority and SQL Tuning

Debug RPGLE, investigate IBM i authority failures and record locks, and tune Db2 SQL using repeatable test cases, job evidence and Visual Explain.

Advanced · 7 sections Interview lab: design, troubleshoot and code

Structure an answer around constraints, trade-offs, and evidence.

Advanced · 3 sections

SQL and RPG file operation reference

Interview questions and explanations

Foundations

IBM i basics — Understand the platform, its object model, and the environment your applications run in.
Objects & library lists — Resolve names correctly and keep development, test, and production environments separate.

Data & database

Files & native file operations — Read, position, update, and diagnose record-oriented database access.
DDS, physical & logical files — Understand record formats, access paths, members, joins, and level checks.
Db2 for i & SQL foundations — Build correct queries with joins, grouping, null handling, and safe parameters.
Embedded SQL & cursors — Handle multirow results, SQL diagnostics, transactions, and resource lifecycles.

RPG & CL development

RPG, RPGLE & RPG IV — Read legacy code and write clear modern RPG with appropriate types and interfaces.
RPG opcodes & indicators — Choose the right operation and explain boundary cases rather than memorizing names.
RPG procedures & data structures — Design typed contracts, manage storage lifetime, and prevent parameter mismatches.
CL & CLLE orchestration — Build reliable wrappers with typed parameters, scoped error handling, and cleanup.
Display files, subfiles & printing — Explain interactive record formats, paging, indicators, and spooled output.

Runtime & work management

Jobs & job queues — Follow a job from submission through execution, output, and completion.
Subsystems, routing & memory pools — Understand workload admission, routing, memory, and operational isolation.
Batch processing & scheduling — Make unattended work restartable, observable, and safe to rerun.
Job logs & diagnostic messages — Read the whole failure chain and preserve the evidence needed to resolve it.

ILE & application design

ILE: modules, programs & services — Understand what gets compiled, bound, activated, and shared.
Binding, calling & signatures — Evolve public interfaces without surprising existing callers.
Activation groups & lifecycle — Reason about storage, open files, commitment scope, and repeated calls.

Messaging & transactions

Data queues & asynchronous work — Design producer-consumer flows with correct payloads and recovery behavior.
Data areas & message queues — Distinguish shared state, job-local state, and operator messaging.
Commitment control & journaling — Define atomic business units and explain what commit and rollback actually cover.
Locks, concurrency & isolation — Diagnose contention and protect correctness without unnecessarily serializing work.

Production engineering

Debugging RPG, CL & batch — Reproduce failures in the correct job and inspect the code that is actually running.
System operations & recovery — Connect application behavior to storage, output, backups, and system change.
Security & authorities — Apply least privilege across libraries, objects, programs, SQL, and remote entry points.
APIs, JSON & integration — Expose business logic and connect systems with explicit contracts and reliable failure handling.
Performance & SQL tuning — Measure elapsed time, query plans, I/O, and contention before choosing a fix.

Interview practice

Real-world design scenarios — Practice explaining an end-to-end solution and defending its trade-offs.
Production troubleshooting drills — Work from symptoms to evidence, diagnosis, correction, and verification.
Tricky questions & common myths — Spot missing assumptions and answer with precise, defensible boundaries.

Practise and troubleshoot

RPGLE and CLLE coding exercises: tasks, examples and test cases.
Common IBM i issues: symptoms, diagnostic steps and verification.

AI on IBM i and development articles

MCP4i: Learning MCP by Building a Server in RPGLE — A practical walkthrough of learning the Model Context Protocol by building a controlled, read-only RPGLE server for IBM i.
IBM i MCP Server: Explore Jobs and System Health from VS Code — A practical RPG developer's guide to IBM's SQL-backed MCP monitoring tools, their limits, and connecting them to a VS Code agent.