Warm up with duplicate transaction detector diagnostic drill
Easy SQL arena: GROUP BY, HAVING, tie-safe ordering, and read-only analysis
A learner is about to attempt the full duplicate transaction detector arena. Build a smaller but realistic diagnostic that exposes whether they understand GROUP BY, HAVING, tie-safe ordering, and read-only analysis. You are working inside an analytics warehouse, and the arena only clears when the result is safe, deterministic, and explainable.
Learn to apply GROUP BY, HAVING, tie-safe ordering, and read-only analysis in an analytics warehouse while explaining the invariant, safety constraints, and hidden edge cases.
- Demonstrates GROUP BY, HAVING, tie-safe ordering, and read-only analysis
- Handles the visible sample and hidden edge cases
- Keeps output deterministic and explainable
- Stays read-only
Charging editor core
Test Results
Run the visible checks when your first pass is ready.
Clear Protocol
Rewards
Mission Route
Hints
Hints are metered and logged for No Hint Hero runs.
Genie Mentor Core
Hint protocol / contextual guardrails active