Databases & Data Storage

ORM

Definition

Object-Relational Mapping (ORM) is a programming technique for converting data between incompatible type systems in object-oriented programming languages. This creates a "virtual object database" that can be used from within the programming language.

Why It Matters

ORMs allow developers to work with a database using the objects and classes of their preferred programming language, instead of writing raw SQL strings. This can make development faster and less error-prone.

Contextual Example

A Python developer using the SQLAlchemy ORM could write `user = session.query(User).filter_by(name='Alice').first()` instead of `SELECT * FROM users WHERE name = 'Alice' LIMIT 1;`. The ORM translates the Python code into SQL.

Common Misunderstandings

  • ORMs are convenient but can sometimes generate inefficient SQL queries. For performance-critical code, developers may still choose to write raw SQL.
  • Popular ORMs include SQLAlchemy for Python, Hibernate for Java, and Entity Framework for .NET.

Related Terms

Last Updated: December 19, 2025