12 practical SQL Fundamentals questions with an explanation after every answer. No timer, no signup — about 8 minutes.
This SQL Fundamentals quiz is a Practical fundamentals check. It covers SELECT, WHERE, joins, aggregation, GROUP BY, HAVING, indexes, primary keys, transactions, NULLs, and ordering. The quiz has 12 questions, takes about 8 minutes, and a score around 8 out of 12 means you have a workable baseline.
The 12 questions on this page are built for practical query fluency screening. They focus on practical decisions you would make while building, debugging, querying, or operating real projects.
Three examples from the 12-question quiz. Answers stay hidden until you reveal them.
What does COMMIT do in a transaction?
COMMIT makes the transaction changes durable. ROLLBACK cancels uncommitted changes.
Which predicate checks for missing NULL values?
Use IS NULL or IS NOT NULL. Comparisons like = NULL do not behave as ordinary equality because NULL means unknown.
Which clause controls result order?
ORDER BY sorts result rows. Without it, SQL does not guarantee row order.
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