SQL Practice Problems
150 solved SQL problems across Beginner, Intermediate, Advanced, and Expert & Real-World tiers — every solution executed against a real dataset, with the actual output and a full explanation for each.
SQL Practice — Beginner (Problems 1-30)
beginner30 warm-up problems covering SELECT, WHERE, ORDER BY, LIMIT, DISTINCT, filtering operators, and basic aggregates — every one solved, run against real data, and explained.
SQL Practice — Intermediate (Problems 31-70)
intermediate40 problems on joins (inner, left, self), correlated subqueries, GROUP BY/HAVING at scale, date range filtering, and string/date functions — every one solved, run against real data, and explained.
SQL Practice — Advanced (Problems 71-110)
advanced40 problems on window functions — RANK, DENSE_RANK, ROW_NUMBER, NTILE, LAG, LEAD, running totals, and moving averages — every one solved, run against real data, and explained.
SQL Practice — Expert & Real-World (Problems 111-150)
advanced40 real-interview-style problems on recursive CTEs, cohort analysis, retention, Pareto analysis, medians, and data-quality validation — every one solved, run against real data, and explained, including two problems where the given solution has a real limitation worth understanding.