For SQL practice, choose SQL Quiz Book

SQL Quiz Book

Learn commonly used, practical SQL through problems organized by topic. Every problem visualizes table transformations to show how SQL processes data. Covers standard SQL and PostgreSQL.

anomaly4 sets

Anomaly Detection — Learn Moving Averages, z-Scores, and IQR-Based Outlier Detection from the BasicsVol.1 · Q1–5Basic

Anomaly Detection — Learn Rankings, cumulative sums, PARTITION BY, and aggregate alerts from the BasicsVol.1 · Q6–10Basic

Anomaly Detection — Learn MAD, EWMA, and Consecutive Anomaly Detection in PracticeVol.1 · Q1–5Advanced

Anomaly Detection — Learn Rolling z-Scores, Seasonality, and Composite Signals in PracticeVol.1 · Q6–10Advanced

batch10 sets

Batch Processing — Learn SELECT, JOIN, Aggregation, Updates, and CTEs from the BasicsVol.1 · Q1–5Basic

Batch Processing — Learn SELECT through JOIN, aggregation, updates, and CTEs from the BasicsVol.1 · Q6–10Basic

Batch Processing — Learn DISTINCT, NULL, LIKE, EXISTS, window functions, and UPSERT from the BasicsVol.2 · Q1–5Basic

Batch Processing — Learn NULL, LIKE, EXISTS, window functions, and UPSERT from the BasicsVol.2 · Q6–10Basic

Batch Processing — Learn CTEs, Window Functions, Running Totals, and Pivots in PracticeVol.1 · Q1–5Advanced

Batch Processing — Learn Running Totals, Pivots, and Recursive CTEs in PracticeVol.1 · Q6–10Advanced

Batch Processing — Learn UPSERT, bulk updates, archiving, and deduplication in PracticeVol.2 · Q1–5Advanced

Batch Processing — Learn Logical deletion, pagination, incremental updates, and monitoring in PracticeVol.2 · Q6–10Advanced

Batch Processing — Learn Correlated subqueries, CTEs, LAG/LEAD, and recursive CTEs in PracticeVol.3 · Q1–5Advanced

Batch Processing — Learn LATERAL, JSONB, differential updates, EXPLAIN, and ROLLUP in PracticeVol.3 · Q6–10Advanced

behavior4 sets

Behavioral Analytics — Learn Cohorts, Retention, Funnels, and Churn from the BasicsVol.1 · Q1–5Basic

Behavioral Analytics — Learn First Touch, Gap-and-Island, Recursive CTEs, and Segmentation from the BasicsVol.1 · Q6–10Basic

Behavioral Analytics — Learn Window Functions, Recursive CTEs, and Multi-Period Analysis in PracticeVol.1 · Q1–5Advanced

Behavioral Analytics — Learn Attribution, Sessionization, RFM, and Hierarchical SQL in PracticeVol.1 · Q6–10Advanced

benchmark4 sets

Competitive Analysis — Learn Core Analysis Techniques with Window Functions from the BasicsVol.1 · Q1–5Basic

Competitive Analysis — Learn Anti-Joins, Moving Averages, and Cumulative Share from the BasicsVol.1 · Q6–10Basic

Competitive Analysis — Learn Multiple CTEs, Frame Clauses, and FIRST_VALUE in PracticeVol.1 · Q1–5Advanced

Competitive Analysis — Learn LAG/LEAD, RANK, PERCENT_RANK, and Scoring in PracticeVol.1 · Q6–10Advanced

cardinality4 sets

Cardinality — Learn 1:1, 1:N, and N:N Table Relationships from the BasicsVol.1 · Q1–5Basic

Cardinality — Learn Table Relationships with LEFT JOIN, ROW_NUMBER, and CTEs from the BasicsVol.1 · Q6–10Basic

Cardinality — Learn Relationships with EXISTS, LATERAL, and Recursive CTEs in PracticeVol.1 · Q1–5Advanced

Cardinality — Learn ROW_NUMBER, FULL OUTER JOIN, and FILTER in PracticeVol.1 · Q6–10Advanced

cte4 sets

CTEs and the WITH Clause — Learn Query Organization and Refactoring from the BasicsVol.1 · Q1–5Basic

CTEs and the WITH Clause — Learn Query Organization and Refactoring from the BasicsVol.1 · Q6–10Basic

CTEs and the WITH Clause — Learn WITH, Multiple CTEs, and Recursive CTEs in PracticeVol.1 · Q1–5Advanced

CTEs and the WITH Clause — Learn Multiple CTEs, Recursive CTEs, Running Totals, LEAD, and RFM in PracticeVol.1 · Q6–10Advanced

duplication4 sets

Duplicate Data Management — Learn DISTINCT, ROW_NUMBER, and UNION from the BasicsVol.1 · Q1–5Basic

Duplicate Data Management — Learn DISTINCT, EXCEPT, INTERSECT, and Representative-Row Selection from the BasicsVol.1 · Q6–10Basic

Duplicate Data Management — Learn DISTINCT ON, Window Functions, LAG, and EXCEPT in PracticeVol.1 · Q1–5Advanced

Duplicate Data Management — Learn Window Functions, Set Operations, and CTEs in PracticeVol.1 · Q6–10Advanced

events4 sets

Event Modeling — Learn Sessions, behavior paths, and DAU/MAU from the BasicsVol.1 · Q1–5Basic

Event Modeling — Learn Funnels, cohorts, cumulative aggregation, and segmentation from the BasicsVol.1 · Q6–10Basic

Event Modeling — Learn Funnels, Session IDs, Retention, and Recursive CTEs in PracticeVol.1 · Q1–5Advanced

Event Modeling — Learn Sessionization, Attribution, Gaps and Islands, and Recursive CTEs in PracticeVol.1 · Q6–10Advanced

grouping4 sets

GROUP BY — Learn Grouping, Aggregation, and Conditional Aggregation from the BasicsVol.1 · Q1–5Basic

GROUP BY — Learn JOIN Aggregation, DATE_TRUNC, Binning, and STRING_AGG from the BasicsVol.1 · Q6–10Basic

GROUP BY — Learn Pivoting, Time-Series Aggregation, ROLLUP, Share Analysis, and List Aggregation in PracticeVol.1 · Q1–5Advanced

GROUP BY — Learn COUNT DISTINCT, FILTER, ROLLUP, two-stage aggregation, and share analysis in PracticeVol.1 · Q6–10Advanced

join8 sets

JOIN — Learn Table Joins and Row-Count Changes from the BasicsVol.1 · Q1–5Basic

JOIN — Learn Table-Join Fundamentals from the BasicsVol.1 · Q6–10Basic

JOIN — Learn Practical Join Patterns from the BasicsVol.2 · Q1–5Basic

JOIN — Learn Multi-Table Joins from the BasicsVol.2 · Q6–10Basic

JOIN — Learn Practical Join Patterns and Row-Count Changes in PracticeVol.1 · Q1–5Advanced

JOIN — Learn Practical Joins and Subqueries in PracticeVol.1 · Q6–10Advanced

JOIN — Learn Practical Join Patterns in PracticeVol.2 · Q1–5Advanced

JOIN — Learn Complex Join Patterns in PracticeVol.2 · Q6–10Advanced

kpi4 sets

KPI Analysis — Learn DAU/MAU, CVR, Retention, and ARPU from the BasicsVol.1 · Q1–5Basic

KPI Analysis — Learn Moving Averages, Sales Mix/Pareto, Rankings, HAVING, and Churn Rate from the BasicsVol.1 · Q6–10Basic

KPI Analysis — Learn Moving Averages, Funnels, Cohort Retention, and Pareto Analysis in PracticeVol.1 · Q1–5Advanced

KPI Analysis — Learn MoM Growth, NTILE Segmentation, Funnel CVR, Cohort Retention, and Recursive CTEs in PracticeVol.1 · Q6–10Advanced

null4 sets

NULL — Learn IS NULL, COALESCE, COUNT, and LEFT JOIN from the BasicsVol.1 · Q1–5Basic

NULL — Learn Propagation, GROUP BY, CASE WHEN, Sort Order, and FULL OUTER JOIN from the BasicsVol.1 · Q6–10Basic

NULL — Learn GROUP BY, NOT IN Traps, FILTER Aggregation, and Multiple LEFT JOINs in PracticeVol.1 · Q1–5Advanced

NULL — Learn NOT IN traps, aggregate NULLs, JOIN conversion, NULLIF, and division by zero in PracticeVol.1 · Q6–10Advanced

perf12 sets

Performance Optimization — Learn EXPLAIN, Index Scan, Sargability, and Top-N from the BasicsVol.1 · Q1–5Basic

Performance Optimization — Learn Composite Indexes, JOIN Strategies, and Keyset Pagination from the BasicsVol.1 · Q6–10Basic

Performance Optimization — Learn Type Conversion, LIKE, OR/UNION, and Covering Indexes from the BasicsVol.2 · Q1–5Basic

Performance Optimization — Learn NOT IN/NULL, Anti Joins, FILTER, and Sorting from the BasicsVol.2 · Q6–10Basic

Performance Optimization — Learn N+1, Three-Valued Logic, Half-Open Intervals, and Partial Indexes from the BasicsVol.3 · Q1–5Basic

Performance Optimization — Learn Type Conversion, ROW_NUMBER, and Keyset Pagination from the BasicsVol.3 · Q6–10Basic

Performance Optimization — Learn Composite Indexes, Keyset, Pre-Join Aggregation, and Recursive CTEs in PracticeVol.1 · Q1–5Advanced

Performance Optimization — Learn Covering Indexes, LATERAL, MVs, and Partitioning in PracticeVol.1 · Q6–10Advanced

Performance Optimization — Learn Practical INDEX Design, LATERAL, and Top-N in PracticeVol.2 · Q1–5Advanced

Performance Optimization — Learn Anti Joins, FILTER Pivots, Sort Elimination, and Top-N in PracticeVol.2 · Q6–10Advanced

Performance Optimization — Learn LATERAL Top-N, Expression Indexes, and Composite-Index Column Order in PracticeVol.3 · Q1–5Advanced

Performance Optimization — Learn Expression Indexes, LAG/LEAD, Keyset Pagination, and LATERAL in PracticeVol.3 · Q6–10Advanced

predicate4 sets

Predicates — Learn Comparison, BETWEEN, LIKE, IS NULL, IN, and EXISTS from the BasicsVol.1 · Q1–5Basic

Predicates — Learn Dynamic Lists, NULL Traps, EXISTS, and Compound Conditions from the BasicsVol.1 · Q6–10Basic

Predicates — Learn EXISTS, IN subqueries, ANY/ALL, and IS DISTINCT FROM in PracticeVol.1 · Q1–5Advanced

Predicates — Learn LIKE, BETWEEN, ANY, and Compound EXISTS in PracticeVol.1 · Q6–10Advanced

recursive-cte4 sets

Recursive CTE — Learn Organization Charts, Category Hierarchies, and Tree Structures from the BasicsVol.1 · Q1–5Basic

Recursive CTE — Learn Number Sequences, BOM Expansion, Graph Paths, and Cycle Detection from the BasicsVol.1 · Q6–10Basic

Recursive CTE — Learn Window Functions, Graph Exploration, and RBAC/BOM Expansion in PracticeVol.1 · Q1–5Advanced

Recursive CTE — Learn Graph Exploration, RBAC, BOM Expansion, and Double Recursion in PracticeVol.1 · Q1–5Advanced

statistics4 sets

Statistical Analysis — Learn Aggregate Functions, Percentiles, Standard Deviation, and Moving Averages from the BasicsVol.1 · Q1–5Basic

Statistical Analysis — Learn CORR, Linear Regression, RANK, NTILE, and LAG from the BasicsVol.1 · Q6–10Basic

Statistical Analysis — Learn Ranking, period comparisons, cumulative analysis, and correlation coefficients in PracticeVol.1 · Q1–5Advanced

Statistical Analysis — Learn Segment Correlation, Residual Analysis, Percentiles, and Moving Averages in PracticeVol.1 · Q6–10Advanced

subquery4 sets

Subqueries — Learn Scalar, IN, EXISTS, FROM-Clause, Correlated, and CTE Comparison from the BasicsVol.1 · Q1–5Basic

Subqueries — Learn Scalar, IN, EXISTS, FROM-Clause, Correlated, and CTE Comparison from the BasicsVol.1 · Q6–10Basic

Subqueries — Learn Correlated, HAVING + SQ, Derived Table × JOIN, and Multi-Level Nesting in PracticeVol.1 · Q1–5Advanced

Subqueries — Learn CASE × SQ, Multiple EXISTS, Top-N Correlation, and Multi-Level CTEs in PracticeVol.1 · Q6–10Advanced

transform4 sets

Data Shaping and Transformation — Learn CAST, COALESCE, CASE, and string/date/numeric functions from the BasicsVol.1 · Q1–5Basic

Data Shaping and Transformation — Learn CAST, COALESCE, CASE, and string/date/numeric functions from the BasicsVol.1 · Q6–10Basic

Data Shaping and Transformation — Learn TO_CHAR, SPLIT_PART, Reduced-Tax-Rate Rounding, and NULL-Safe Aggregation in PracticeVol.1 · Q1–5Advanced

Data Shaping and Transformation — Learn LPAD/CONCAT_WS, AGE/INTERVAL, FILTER Aggregates, and Regular Expressions in PracticeVol.1 · Q6–10Advanced

window8 sets

Window Functions — Learn Ranking, Running Totals, Moving Averages, and Latest-Row Selection from the BasicsVol.1 · Q1–5Basic

Window Functions — Learn Ranking, Running Totals, Moving Averages, and Latest-Row Extraction from the BasicsVol.1 · Q6–10Basic

Window Functions — Learn Analytical Functions and Build Data Marts from the BasicsVol.2 · Q1–5Basic

Window Functions — Learn Analytical Functions and Data Mart Design from the BasicsVol.2 · Q6–10Basic

Window Functions — Learn LAG/LEAD, NTILE, Moving Averages, FIRST/LAST VALUE, and CTEs in PracticeVol.1 · Q1–5Advanced

Window Functions — Learn NTILE, PERCENT_RANK, CTEs, LAG + LEAD, and Moving Averages in PracticeVol.1 · Q6–10Advanced

Window Functions — Learn NTILE, Frames, PERCENT_RANK, Month-over-Month Growth, and Top-N in PracticeVol.2 · Q1–5Advanced

Window Functions — Learn Session Analysis, Moving Averages, and Reusable Window Patterns in PracticeVol.2 · Q6–10Advanced