SQL Quest

Lessons, hints, explained solutions, the in-browser PostgreSQL editor and practice answer checks in your browser are available. Graded assessments, recorded progress from answer checks and new certificates aren't available yet.

Curriculum

Learn SQL, one runnable lesson at a time

12 tracks, 151 lessons and 625 graded exercises. Start at the beginning, follow a career pathway, or take the placement diagnostic to find your starting point. Every lesson runs PostgreSQL in your browser.

  1. 01SQL FoundationsBeginnerFreeWhat databases are, how tables connect, and how to ask your first questions in SQL.10 lessons · 41 exercises · datasets: starter, shop
  2. 02Retrieving and Filtering DataBeginnerFreeAsk precise questions: calculate, filter, sort and page through exactly the rows you need.14 lessons · 56 exercises · datasets: starter, shop, people
  3. 03Aggregation and Business ReportingBeginner1 free · 12 membersTurn thousands of rows into the counts, totals, rates and KPIs that businesses run on.13 lessons · 57 exercises · datasets: shop, stay, clinic
  4. 04Joining TablesIntermediate1 free · 14 membersCombine tables with confidence: match rows on keys, keep or find what is missing, and never double count.15 lessons · 60 exercises · datasets: starter, shop, people, freight
  5. 05Subqueries and Advanced FilteringIntermediate1 free · 11 membersBreak hard questions into steps: queries that feed queries, EXISTS, CTE pipelines, recursion and set operations.12 lessons · 47 exercises · datasets: shop, bank, people
  6. 06Intermediate and Advanced AnalyticsAdvanced1 free · 13 membersWindow functions, rankings, running totals, period comparisons, time series, cohorts and retention.14 lessons · 56 exercises · datasets: shop, saas, stay, people
  7. 07Data Cleaning and TransformationIntermediate1 free · 12 membersTurn messy operational data into trustworthy, analysis-ready tables.13 lessons · 52 exercises · datasets: shop, clinic, freight, people
  8. 08Database Creation and ManagementIntermediate1 free · 14 membersDesign tables that protect their data, change rows safely, and evolve a schema without breaking what depends on it.15 lessons · 60 exercises · datasets: starter, shop, people
  9. 09Performance and Query OptimizationAdvanced1 free · 10 membersRead query plans, build the right indexes and rewrite slow queries on a large event store.11 lessons · 39 exercises · datasets: perf, shop
  10. 10SQL for Business and FinanceIntermediate1 free · 12 membersRevenue, margin, the general ledger, budgets, reconciliation, banking and workforce analytics, written the way finance teams define them.13 lessons · 53 exercises · datasets: ledger, bank, shop, people
  11. 11SQL for Data Analytics and Business IntelligenceAdvanced1 free · 10 membersDesign trustworthy metrics on a star schema: KPIs, funnels, churn, lifetime value and datasets ready for dashboards.11 lessons · 46 exercises · datasets: mart, saas, shop
  12. 12SQL Interview and Career PreparationIntermediate1 free · 9 membersPractise the questions interviewers actually ask, on schemas you have never seen, and learn to explain every line.10 lessons · 58 exercises · datasets: shop, people, clinic, ledger, saas, mart, freight, bank