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Computer Programmer skills: what to learn first, and what can wait

Shops that still hire computer programmers want someone who can pick up a written spec and change a program that other programs depend on, without breaking last night's batch. Learn one core business language well, get fluent in SQL, and practise reading code you didn't write. Cloud certificates and trendy frameworks can wait.

31 open jobs

Step one

Gets you the interview

One core business language: COBOL, RPG, Java or C#Programmer postings name the language in the title line, and the screener filters on it. Learn its file handling and record layouts, not just loops and syntax. A COBOL candidate who can explain a copybook and a PERFORM loop gets the call.

SQL against real business tablesYou'll write queries against policy, claims or inventory tables with odd column names and years of messy data. Joins, GROUP BY, updates inside a transaction and knowing what a lock does are what the phone screen checks.

Batch jobs and job controlMuch of the work runs overnight: JCL on a mainframe, CL on IBM i, or scheduled jobs in Control-M or Windows Task Scheduler. Knowing how a job reads a file, writes a report and hands off to the next step puts you ahead of candidates who only know web apps.

Source control and the shop's promotion toolGit on newer teams, Endevor or ChangeMan on mainframe teams. Say which you've used and how code moves from your library to production.

Step two

Gets you the offer

Impact analysis before you touch anythingThe technical round often hands you a change like adding a field to a customer record. Strong candidates first ask which programs, copybooks and downstream extracts read that record, and how they'd search for them. That one habit prevents most production breaks.

Building your own test dataSpecs rarely come with test cases. Showing how you'd copy a slice of production, mask the names and account numbers, and set up edge cases like a zero balance or a missing date tells the panel you won't rely on QA to find your bugs.

Debugging from a dump or a logWhen a job abends at night, you read the abend code, the SYSOUT or the stack trace, find the bad record and decide whether to restart. Walk through one real failure you fixed and the interviewer relaxes.

Reading a spec and pushing back on gapsPointing out that the analyst's spec never says what happens to records already in progress shows judgement. Hiring managers remember it.

Step three

Gets you promoted

Writing requirements with the businessSitting with the finance office or the claims team and turning their complaint into exact rules is the move from programmer to programmer analyst. Start by drafting the spec for your own tickets and asking the analyst to review it.

Owning the release and the rollbackLeads plan the weekend release, write the back-out steps and present them at the change advisory board. Volunteer for one and you'll learn more than any course teaches.

Exposing old systems through APIsModernization projects wrap COBOL or RPG programs in REST services with z/OS Connect, IBM i web services or a thin Java layer. Knowing both sides makes you the bridge those projects can't staff easily.

Code review and coaching juniorsReviewing a trainee's first changes against the shop's standards, and explaining why a shortcut is risky, is how managers spot a future lead.

Certificates worth your time

Certificate	Best for	Effort	Worth it?
Oracle Certified Professional: Java SE Developer	Programmers at Java shops who want a recognised keyword on the résumé	a couple of months of steady evening study	A fair, hard exam. Worth it early in your career if local postings mention Java, less useful once you have solid work to point to.
Microsoft Certified: Azure Developer Associate	C# programmers on teams moving business apps to Azure	a few weekends if you already deploy to Azure	Useful only where the company is on Azure. It shows you can ship and debug in the cloud, which a language certificate doesn't.
IBM Z Xplore digital badges	Newcomers trying to break into mainframe programming	a few weekends of hands-on labs on a real mainframe	Free and practical. The badges won't land a job alone, but the COBOL and JCL practice gives you real stories for the interview.

Exam names, outlines and badge programs change, so check the current details directly with Oracle, Microsoft or IBM before you start studying.

Put it on your résumé like this

Weak

Maintained COBOL programs and fixed bugs as assigned.

Strong

Traced a recurring abend in the nightly claims batch to a date field shared by 23 COBOL programs, fixed the copybook and all callers in one release, and cut after-hours support calls from 9 a month to 1.

Questions people ask

Is COBOL still worth learning?

If you live near banks, insurers or state agencies, yes. The programs aren't going away quickly, and fewer new people learn the language, so employers train and keep the ones who do. Pair it with SQL and JCL or it won't get you far.

Do I need a computer science degree to get hired as a programmer?

Many postings list one, but shops that struggle to fill legacy roles often accept an associate degree or an internal training program. A small project that reads a file, applies business rules and writes a report helps more.

Should I learn a web framework like React?

Not first. Most computer programmer roles sit behind the screens, in batch jobs, reports and data files. Learn it later if your team starts building web front ends.

How do I practise mainframe skills without a job?

Sign up for IBM's free Z Xplore labs, which give you a real mainframe account. Write a COBOL program, submit it with JCL and fix the errors it throws. That's closer to the job than any tutorial.

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