What Is an ORM? Object-Relational Mapping

What an ORM is

An ORM, which stands for object-relational mapping, is a tool that lets developers work with a relational database using the objects of their programming language, instead of writing raw database queries by hand. Programming languages often organize data as objects, while relational databases store data in tables. An ORM bridges this gap, automatically translating between the objects in your code and the tables in the database, so you can work with data in a way that feels natural to the language.

The problem it solves

There is a mismatch between how object-oriented programs structure data, as objects, and how relational databases structure it, as tables of rows and columns. Without an ORM, developers must write database queries and manually convert between query results and their program's objects, which is repetitive and error-prone. An ORM handles this translation automatically, letting developers focus on their program's logic rather than the details of moving data in and out of the database.

How an ORM works

An ORM maps the classes and objects in your code to the tables and rows in the database. When you work with objects, such as creating, reading, updating, or deleting them, the ORM generates and runs the appropriate database queries behind the scenes, and converts the results back into objects. So instead of writing database queries directly, you interact with your data as ordinary objects, and the ORM takes care of translating those interactions into database operations.

The benefits

ORMs offer several benefits. They let developers work in their familiar programming language rather than switching to writing database queries, which can speed up development and reduce errors. They handle a lot of repetitive translation work automatically. They can make code more readable and maintainable, and often help with database portability, since the ORM can target different database systems. For many applications, an ORM makes working with a database considerably more convenient and productive.

The trade-offs

ORMs also have trade-offs. The automatic translation adds a layer of abstraction that can sometimes generate inefficient queries or hide what is really happening with the database, which can cause performance issues if not understood. Complex or highly optimized database operations may be awkward to express through an ORM, and sometimes developers still drop down to writing queries directly for those cases. Using an ORM well means understanding both its conveniences and its limitations.

Why it matters

ORMs are a common and important tool in modern software development, smoothing the connection between object-oriented code and relational databases. Understanding what an ORM is, and its benefits and trade-offs, clarifies how many applications interact with their databases and why developers reach for these tools. For anyone interested in software development and how programs work with data, the ORM is a valuable concept to understand.

Related on Skillo

See also: What is a database? SQL vs NoSQL explained, What is a framework? Explained.

Sources

• Object-relational mapping - Wikipedia

Published date reflects the original event date (2023-06-27). This article is original Skillo editorial written from the sources above; facts were verified in September 2026.