SQLAlchemy

SQLAlchemy is an open source Python toolkit for working with SQL databases, with an object-relational mapper built on top. It gives you direct access to SQL and a higher-level ORM, so you can choose how much abstraction to use.

SQLAlchemy has two layers. Core provides connections, schema tools and SQL expressions, while the ORM maps Python classes to tables and manages sessions and relationships. It supports many database backends through dialects. Its documentation describes persistence patterns designed for efficient, high-performing database access.

• Core for SQL expressions and connections
• ORM for mapping classes to tables
• Dialects for many database backends
• Session and unit-of-work management
• Migrations through the companion Alembic project

Python developers building data-heavy backends or scripts that need fine control over SQL. Teams that want a mapper they can use at several levels of abstraction will also find it useful.

SQLAlchemy is free and open source under the MIT license. The current documentation covers version 2.1, and older versions have separate docs. Learning the ORM and Core layers takes time, but the tutorial walks through both.