🗄️ Databases & SQL
Run real SQL in your browser — SQLite via Python, no setup.
1→2→3→4→5→6→7→8→9→10→11→12→13→14→15→16→17→18→19→20→21→22→23→24→25→
Lesson 1 — Create a table
basics · 7 min
Lesson 2 — Insert rows
easy · 8 min
Lesson 3 — Filtering with WHERE
medium · 9 min
Lesson 4 — Sorting
medium · 8 min
Lesson 5 — COUNT & SUM
medium · 10 min
Lesson 6 — ORDER BY & LIMIT
medium · 9 min
Lesson 7 — DISTINCT
medium · 8 min
Lesson 8 — LIKE search
medium · 9 min
Lesson 9 — Aggregates
medium · 9 min
Lesson 10 — Indexes (concept)
medium · 9 min
Lesson 11 — Filtering with IN and BETWEEN
medium · 9 min
Lesson 12 — JOIN
hard · 12 min
Lesson 13 — GROUP BY
hard · 12 min
Lesson 14 — HAVING
hard · 11 min
Lesson 15 — Subqueries
hard · 12 min
Lesson 16 — JOINs
hard · 12 min
Lesson 17 — Conditional UPDATE
hard · 10 min
Lesson 18 — Three-table JOIN
hard · 12 min
Lesson 19 — GROUP BY + HAVING + ORDER
hard · 12 min
Lesson 20 — Correlated subquery
hard · 12 min
Lesson 21 — Recursive CTE
hard · 13 min
Lesson 22 — Indexes & EXPLAIN (expert)
hard · 12 min
Lesson 23 — Transactions & rollback
very hard · 15 min
Lesson 24 — Views
very hard · 14 min
Lesson 25 — Ultimate: sales report
★ ultimate · 19 min