database

name	database
description	Guidance for SQLAlchemy 2.0 ORM models, Alembic migrations, database indexes, N+1 query elimination, and safety.

Database Skill Directive

1. **SQLAlchemy 2.0 Declarative**: Define models in `backend/app/models/` using `Mapped[]` and `mapped_column()`. 2. **Alembic Migrations**: Generate migration scripts for all schema changes (`alembic revision --autogenerate -m "..."`). Never modify tables manually in production databases. 3. **Query Optimization**: Avoid N+1 query problems by using `joinedload()` or `selectinload()` when querying relationships. 4. **Indexes & Constraints**: Add indexes to foreign keys and columns frequently used in `WHERE`, `ORDER BY`, or `JOIN` clauses. 5. **Data Safety**: Destructive column drops or table deletions REQUIRE human review and approval.