Data Models & Schema: Defining Your Database Structure with SQLAlchemy

What is a Data Model? A data model defines the structure of your data before it ever touches a database. Think of it as a blueprint : every record must follow this structure, ensuring consistency. Setting Up SQLAlchemy with SQLite SQLAlchemy is Python's most popular ORM (Object-Relational Mapper). It lets you define database tables as Python classes instead of writing raw SQL. from sqlalchemy import create_engine, Column, Integer, String, Text, Numeric, DateTime from sqlalchemy.orm import declarative_base engine = create_engine("sqlite:///items.db", echo=True) Base = declarative_base() Defining the Item Model class Item(Base): __tablename__ = "items" id = Column(Integer, primary_key=True, index=True) name = Column(String, nullable=False) description = Column(Text) price = Column(Numeric(10, 2), nullable=False) created_at = Column(DateTime, default=datetime.utcnow) Each field maps directly to a database column: id -> Primary Key, auto-incremented name -> Required string description -> L