Object-relational mapping (ORM) tools

Key facts

First appeared

1996

Category

technology

Problem solved

ORM tools were created to solve the 'object-relational impedance mismatch,' which refers to the fundamental conceptual differences between object-oriented programming languages and relational databases. This mismatch manifests in issues like granularity (objects can be complex graphs, tables are flat rows), inheritance (relational databases lack direct inheritance support), identity (object identity vs. primary keys), and navigation (object graph traversal vs. relational joins). Before ORMs, developers had to write extensive boilerplate code to manually map data between an application's object model and the database, handle SQL queries, manage connections, and synchronize changes, leading to tedious, error-prone, and less maintainable code.

Platforms

Windows, Cross-platform (where the host language/runtime runs, e.g., JVM, .NET CLR, Python interpreter, Ruby interpreter), macOS, Linux

Related technologies

• .NET (C#, VB.NET)
• JavaScript (Node.js)
• Web frameworks (Spring, ASP.NET Core, Django, Ruby on Rails, Laravel, Express.js)
• Python
• Java
• SQL databases (PostgreSQL, MySQL, SQL Server, Oracle)
• PHP
• Ruby

Notable users

• Microsoft
• Any company building data-driven applications with relational databases and object-oriented languages
• Netflix
• Red Hat
• Google