SQL from Zero

A sixteen-module SQL course in one file, with a SQL engine inside it. Each module teaches one idea — filtering, NULL, grouping, joins, anti-joins, self-joins — then asks for queries against a synthetic revenue-cycle database of claims, denials, encounters, payers and calls. The engine runs what the learner writes and compares the result set, so an answer is marked by what it returns rather than by matching text. Sixty-four exercises, twenty-eight spaced-review questions that each name the earlier module they came from, and a worked walkthrough per module.

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Problem

A learner can copy a query that returns the right rows and still not know the technique — so the next question, phrased differently, defeats them.

Who it helps

Anyone learning SQL from nothing; analysts and revenue-cycle staff who read reports they cannot yet write.

In training

Open in any browser — no login, no server, no internet. Work a module, try its exercises, and let the spaced-review questions bring earlier modules back before they fade. Scoring separates solved unaided from solved after a hint or a reveal, so the score says how much help was needed rather than only whether the answer was right.

Skills shown

Curriculum sequencing, assessment design, immediate feedback, spaced retrieval practice, mastery scoring, and a hand-built SQL parser and evaluator that refuses rather than guesses.