SQLAlchemy 2.0 Patterns Audience: Python developers building database-backed applications Goal: Comprehensive SQLAlchemy 2.0 reference for models, queries, and data access Engine Setup Sync Engine Async Engine (PostgreSQL + asyncpg) Model Definition (2.0 Style) Relationship Patterns One-to-Many Many-to-Many Self-Referential Indexing Strategy Query Patterns Select Queries Async Queries Joins and Eager Loading Aggregations Repository Pattern Query Optimization N+1 Problem Bulk Operations Connection Pooling FastAPI Integration Transactions Checklist - [ ] Using SQLAlchemy 2.0 style (Mapped, mapp…