SQLAlchemy Python ORM

SQLAlchemy is a free and open-source SQL toolkit and Object-Relational Mapping (ORM) library for Python that provides enterprise-level persistence patterns for efficient database access. Created by Michael Bayer (zzzeek) in 2005, SQLAlchemy is the most widely used database library for Python. The current version is 2.0 (released January 2023). Key features: Core (SQL Expression Language): a Pythonic SQL construction toolkit generating SQL statements as Python objects. Provides schema-centric abstraction (tables, columns, constraints) and SQL expression language for building SELECT, INSERT, UPDATE, DELETE programmatically. ORM: maps Python classes to database tables, supporting relationships (one-to-many, many-to-many), eager and lazy loading, cascading, polymorphic inheritance. Session: the ORM interface for managing object persistence, tracking changes and flushing them in a single transaction (unit of work pattern). SQLAlchemy 2.0 style: unified API using select() for both Core and ORM, replacing the legacy Query API. Type annotations: full type hint support with MyPy plugin. Engine and connection pooling with configurable pool size, timeout, recycling. Supports PostgreSQL, MySQL, SQLite, Oracle, SQL Server. Alembic for migrations. Async support via asyncio. Python codebase. MIT.