Tools

• Levels 1-3 use the SQL workbench panel next to each lesson (dialect PostgresQL). It checks syntax and draws your schema. It never runs queries.
• Levels 4-9 use a real Postgres. Level 4 walks through the setup.

The workbench keeps your migrations as files in data/migrations/sql/ (001_...sql, 002_...sql, in order). They are the app's schema history, and every level adds to them.