Object-relational mapping (ORM) in computer software is a programming technique for converting data between incompatible data types in object-oriented programming languages. This creates, in effect, a “virtual object database” that can be used within the programming language. There are both free and commercial packages available that perform object-relational mapping, although some programmers decide to create their own ORM tools.
Hibernate is an object-relational mapping (ORM) for Java language, providing a framework for mapping an object-oriented model domain on a traditional relational database. Hibernate is free software distributed under the GNU Lesser General Public License.
The primary feature is mapping from Java classes to database tables (and from Java data types to SQL data types).
nHibernate is an object-relational mapping (ORM) solution for the Microsoft .NET platform. nHibernate is a port of the popular Java Hibernate for .NET.
Telerik’s object-relational mapping is a powerful framework for mapping objects in your object-oriented model for tables, views, and / or stored procedures. This mapping is done in Visual Studio, and is independent of the source code and database. It is a virtual layer, which can be used within a programming language to access and manipulate data.
Doctrine for PHP is ORM that is at the top of the strong data abstract layer (DBAL). One of the key features is the ability to write queries in an object-oriented SQL dialect called Doctrine Query Language (DQL), inspired by Hibernates HQL. This gives developers a good alternative to SQL that maintains flexibility without requiring unnecessary code duplication.