ORM Basics with SQLAlchemy and Django ORM

June 17, 2025

Object-Relational Mapping (ORM) is a powerful programming technique that simplifies database interactions by allowing developers to interact with databases using high-level programming languages instead of raw SQL queries. Two popular ORM tools in Python are SQLAlchemy and Django ORM. Though they serve similar purposes, they cater to different use cases and frameworks.

What is ORM?

ORM bridges the gap between object-oriented programming and relational databases. It lets developers define database tables as Python classes and rows as instances. This abstraction allows cleaner, more readable code and reduces the risk of SQL injection and syntax errors.

SQLAlchemy ORM

SQLAlchemy is a flexible and powerful ORM toolkit for Python that provides both high-level ORM capabilities and low-level SQL expression language. It is framework-independent, making it ideal for projects that don’t use Django.

Key Features:

Full control over SQL statements.

Support for complex relationships and custom queries.

Works well with multiple databases like PostgreSQL, MySQL, and SQLite.

Basic Example:

python

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from sqlalchemy import Column, Integer, String, create_engine

from sqlalchemy.ext.declarative import declarative_base

from sqlalchemy.orm import sessionmaker

Base = declarative_base()

class User(Base):

__tablename__ = 'users'

id = Column(Integer, primary_key=True)

name = Column(String)

engine = create_engine('sqlite:///users.db')

Base.metadata.create_all(engine)

Session = sessionmaker(bind=engine)

session = Session()

new_user = User(name="John")

session.add(new_user)

session.commit()

Django ORM

Django ORM is a built-in feature of the Django web framework. It tightly integrates with Django’s models and admin interface, making it extremely convenient for rapid web development.

Key Features:

Automatically handles migrations.

Integrated with Django admin, forms, and views.

Uses model inheritance and relationships with minimal code.

Basic Example:

python

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from django.db import models

class User(models.Model):

name = models.CharField(max_length=100)

# Creating a user

user = User(name="Alice")

user.save()

# Querying users

users = User.objects.all()

Conclusion

Both SQLAlchemy and Django ORM offer robust solutions for managing database operations in Python applications. SQLAlchemy is more suitable for developers needing fine-grained control and flexibility, while Django ORM is perfect for rapid development within the Django framework. Choosing the right ORM depends on your project requirements and preferred development style, but either way, ORM simplifies the interaction between code and data.

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