Flask and Database Connection: SQLAlchemy Basic Operations

SQLAlchemy is a popular ORM tool for Python that allows database operations through Python classes/objects, avoiding direct SQL writing. It supports multiple databases (e.g., MySQL, SQLite) and is well-suited for Flask development. Installation requires `pip install flask flask-sqlalchemy`, with additional drivers needed for databases like MySQL. During initialization, configure the Flask application and database connection (e.g., SQLite path), then initialize the SQLAlchemy instance. Data models are defined via classes, where each class corresponds to a table and class attributes represent fields (e.g., the `User` class includes `id`, `username`, etc., with primary key, unique, and non-null constraints). Use `db.create_all()` to generate tables within the application context. Core operations (CRUD): Create (instantiate → `db.session.add()` → `commit()`); Read (`query.all()`/`filter_by()` etc.); Update (modify object attributes → `commit()`); Delete (`db.session.delete()` → `commit()`). Workflow: Configure connection → Define models → Create tables → CRUD operations. The advantage is no need to write SQL, facilitating rapid development.