Learn SQL on real CSV data.

SELECT to GROUP BY in an afternoon.

• Lesson 1 — SELECT & LIMIT — Your first SQL on a real CSV: SELECT * to see everything, LIMIT to take just a few rows.
• Lesson 2 — Picking columns — Select only the columns you need and rename them with AS.
• Lesson 3 — WHERE filters — Filter CSV rows with WHERE: equality, greater/less than, text and numbers.
• Lesson 4 — AND, OR & LIKE — Combine filters with AND/OR and match text patterns with LIKE and % wildcards.
• Lesson 5 — ORDER BY & top-N — Sort results with ORDER BY and combine with LIMIT for top-10 lists.
• Lesson 6 — COUNT — COUNT(*) answers 'how many?' — combine it with WHERE to count matching rows.
• Lesson 7 — SUM, AVG, MIN, MAX — Total a column with SUM, average it with AVG, find extremes with MIN/MAX — on a real CSV, interactively, in your browser..
• Lesson 8 — GROUP BY — GROUP BY is the pivot table of SQL: one row per category with aggregates per group.
• Lesson 9 — Grouping deeper — Group by two columns at once and mix multiple aggregates — on a support-ticket CSV, interactively in your browser..
• Lesson 10 — Your files & beyond — The capstone: two review challenges, then where to go next — query your own CSVs, join files, and graduate to full DuckDB SQL, all in the browser..

Because the data is real.

• 01

  A real engine, zero setup

  Queries execute in your browser the moment you open a lesson — no database to install, no sandbox account.

• 02

  Result-checked exercises

  Your query and a reference both run on the data and the results are compared — write it your way.

• 03

  It ends on YOUR files

  The same grammar works on the site's SQL tool with your own CSVs — and graduates to full DuckDB for joins, windows and big files.

• 04

  Honest scope

  This course covers the core every dialect shares. When you outgrow it, you'll know exactly what to look up.

Start with Lesson 1 — SELECT and LIMIT, or jump straight to querying your own file.