Original SQL practice datasets

Explore the five fictional SQL Trail data worlds, their table grains, keys, relationships, edge cases, and learning uses.

This public page is designed to answer the learning question directly and then point to the interactive workspace only when practice is useful.

Each original dataset page explains the fictional domain, schema complexity, tables, grains, keys, relationships, row counts, and intentional edge cases.

Learning use is explicit: datasets are tied to modules, reviews, playground practice, and capstone work without requiring the app runtime to understand the schema.

Downloadable SQL or CSV formats are described only when the product actually exposes them; otherwise provenance and local seeded execution remain the canonical facts.

The links below are canonical public resources. They render as normal anchors and do not require the product runtime.

Public pages explain concepts and show verified examples. The `/app` workspace adds the editor, PGlite worker, hidden variants, drafts, review scheduling, and mastery evidence.