SQL certification exam — passed with 87% after 4 weeks, here's how I structured prep
I've been using SQL at work for about 2 years but mostly just SELECT queries, JOINs, and the occasional GROUP BY. When I decided to get certified I realized quickly how much I'd been ignoring. Window functions, subquery optimization, transaction isolation levels — these are things I'd seen mentioned but never actually needed day to day. The exam made sure I knew them.
My study plan was 4 weeks at about 1.5 hours per day. Week 1 was all foundational review — normalization, keys, constraints, basic DML. Week 2 I went deep on JOINs — all types, not just INNER — and aggregate functions. Week 3 was where it got hard: subqueries, CTEs, and window functions like ROW_NUMBER, RANK, and DENSE_RANK. Week 4 I focused entirely on practice questions and drilling anything I got wrong.
The actual exam leaned harder on query interpretation than I expected — given a query, tell me what it returns, or which query produces a specific result. Writing queries from scratch was less common. Make sure you can trace through nested queries mentally, because on a timed exam you can't just run it to check. I finished in about 55 minutes with time to review flagged questions.
4 weeks sounds about right for someone with working SQL experience. I tried to rush it in 2 weeks with an 81% — passed but felt shaky on a bunch of questions. Don't underestimate the theory side just because you use the language daily.
Which certification specifically? There are a few SQL certs out there — Oracle, Microsoft, vendor-neutral ones. The difficulty and content distribution varies pretty significantly between them. Would help to know which exam you sat for.
The query interpretation questions are no joke. I work with SQL daily and still had to slow way down on some of them. Tracing a multi-level subquery with aggregate conditions in your head is a different skill from just writing queries that work.
Window functions were my weak spot too. I spent about 4 hours just on PARTITION BY and ORDER BY inside OVER() clauses before it clicked. The difference between RANK and DENSE_RANK is exactly the kind of detail that shows up in answer choices designed to catch you.