ORM

Technology & Computing abbreviation · Programming

ORM
Stands forObject-relational mapping
CategoriesTechnology & Computing

ORM stands for Object-relational mapping, a programming abbreviation.

A technique, and the libraries implementing it, that maps database tables to classes in object-oriented code, so developers work with objects instead of writing SQL by hand. Hibernate, Entity Framework, Django's ORM, SQLAlchemy, ActiveRecord and Prisma are examples.

Example: The ORM generated 400 queries for one page load, a classic N+1 problem.

Usage notes

ORMs speed up development and use parameterized queries that guard against SQL injection, but they can hide inefficient queries; the "N+1 query problem" is the best-known pitfall. The underlying mismatch between objects and relational tables is called the object-relational impedance mismatch. Most ORMs let developers fall back to raw SQL for complex queries.

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