Don’t memorize SQL. Learn to think in queries.

1. 01Ask→
2. 02Understand→
3. 03Write→
4. 04Run→
5. 05Solve

Harry asks. Hermione explains. You write the query.

A real SQL playground, right in the lesson.

SELECT id, name, country
FROM customers
WHERE country <> 'USA';

From your first SELECT to real-world analytical SQL

Eleven chapters, organized around questions Harry actually needs to answer — not a list of syntax to memorize.

1. 00Before SQL1 lesson
2. 01Asking Questions1 lesson
3. 02Filtering2 lessons
4. 03Aggregation4 lessons
5. 04Joins3 lessons
6. 05Subqueries2 lessons
7. 06CTEs1 lesson
8. 07Window Functions5 lessons
9. 08Analytics7 lessons
10. 09Problem Solving8 lessons
11. 10Projects4 lessons

Every concept comes with a challenge.

You don’t learn SQL by reading SQL. You learn by asking questions, forming hypotheses, writing queries, running them, seeing what happened, and trying again.