IBM i Developer Interview Roadmap

What This Lesson Prepares You For

This lesson is a map, not a technical deep dive. It explains how the Interview and Professional Readiness lessons fit together, what an IBM i developer interview typically covers, and how to use the rest of this course to prepare for one with realistic expectations.

Concepts to Revise First

Before working through this batch, you should already be comfortable with the foundation-level material from earlier in this course:

• RPGLE basics: program structure, variables, IF/SELECT, loops, and built-in functions.
• Native RPGLE file I/O: dcl-f, CHAIN, %FOUND, WRITE, UPDATE, DELETE.
• CLLE basics: what CLLE is for, and simple orchestration with MONMSG.
• SQLRPGLE basics: SELECT INTO, SQLCODE, and how embedded SQL relates to native file I/O.
• Display files and subfiles: how a screen program is structured, and how a subfile lists multiple rows.
• The basic troubleshooting flow: job log first, then debugging tools if needed.

If any of those feel shaky, it is worth revisiting them before spending time on interview-specific practice. Interviewers can usually tell the difference between someone who has memorized a definition and someone who actually understands the concept behind it.

Common Interview Questions

For an entry-level or junior IBM i developer role, questions tend to cluster around a few themes:

• "Walk me through what happens when this RPGLE program runs."
• "What is the difference between a physical file and a logical file?"
• "When would you use CLLE instead of RPGLE, or the other way around?"
• "How would you look up one record by key in RPGLE?"
• "What is a subfile, and why would you use one instead of just printing a list?"
• "How would you start troubleshooting a program that isn't working?"

Good Beginner-Level Answers

A good beginner-level answer is honest about your current level while still showing real understanding. For example, instead of trying to sound like a ten-year veteran, a strong answer to "what is a subfile?" might be: "A subfile lets a 5250 screen show many rows at once, like a list of orders, instead of one record at a time. You load it by writing multiple subfile records, then display it with the subfile control record format." This is short, technically correct, and shows real understanding without overselling your experience.

Scenario-Based Questions

Many interviewers move beyond definitions into small scenarios, such as: "A user says a screen shows the wrong customer balance. How would you start looking into that?" or "A batch job usually finishes by 6 AM, but today the report is missing. What would you check first?" These questions are covered in depth in later lessons in this batch, particularly Debugging Scenario-Based Questions and Real Support Ticket Analysis for Beginners.

How to Explain Your Thinking

Interviewers are often more interested in how you reason through a problem than whether you land on the exact right answer instantly. A useful habit is to say your thinking out loud, in order: what you would check first, why that check comes first, and what you would do next depending on what you find. This mirrors the actual troubleshooting flow covered in the Basic Troubleshooting Flow for IBM i Developers lesson: job log first, then narrow down from there, rather than guessing at a root cause immediately.

Common Weak Answers to Avoid

• Reciting a memorized definition without being able to apply it to a small scenario.
• Claiming familiarity with tools or patterns you have not actually used, which usually becomes obvious with one follow-up question.
• Jumping straight to "I'd just start debugging" without mentioning the job log or the actual symptom first.
• Treating every question as a trivia question instead of an opportunity to explain reasoning.

Practical Examples

Imagine being asked: "What is the difference between CHAIN and SETLL in RPGLE?" A weak answer restates both keywords without contrast. A better answer explains the relationship: "CHAIN retrieves a specific record by key and tells you with %FOUND whether it existed. SETLL positions you at or after a key without retrieving a record itself, which is usually followed by READE to process a group of matching records." This kind of answer shows the concepts connect to each other, not just that you can name them.

Mini Practice Task

Before moving to the rest of this batch, write down, in your own words, one-paragraph answers to these three questions: What is IBM i, in simple terms? What is the difference between a physical file and a logical file? What is one thing you would check first if a report did not generate overnight? Keep your answers short and practical, not textbook-perfect. You will build on this habit throughout the rest of this batch.

Quick Recap

• This batch focuses on explaining IBM i concepts clearly, not on guaranteeing any interview outcome.
• Strong answers connect concepts to small scenarios rather than reciting definitions.
• Explaining your reasoning step by step matters as much as reaching the right answer.
• The rest of this batch covers RPGLE, RPGLE file I/O, CLLE, SQLRPGLE, display files and subfiles, debugging, and realistic support ticket scenarios, in that order.

Try Asking the AI Tutor

Use the AI Tutor to practice explaining IBM i concepts out loud, the way you would in an actual interview. For example, try asking:

• "Can you ask me a beginner-level IBM i interview question and give me feedback on how I answer it?"
• "How would I explain the difference between CHAIN and SETLL to someone who has never used RPGLE?"