ORM

Object-Relational Mapping (ORM) converts data between incompatible type systems in OO languages . This creates, in effect, a virtual object database that can be used from within the programming language.

ORM is widely used in the following languages (limited list, See [[wikipedia:List_of_object-relational_mapping_software|Wikipedia List of ORM Software):

• C++,
  • LiteSQL, ODB, Wt::Dbo, QxOrm
• Cocoa (* Objective-C)
  • Enterprise Objects and Core Data
• Java,
  • Apache Cayenne, EclipseLink, Enterprise Java Beans, Hibernate, iBATES, Java Data Objects, Java Persistence API (JPA), Oracle TOPLink.
• Microsoft .Net
  • ADO.net, DatabaseObjects, Dapper, iBATES, LINQ to SQL, NHibernate.
• Object Pascal or former known as Delphi
• PHP
  • Doctrine, Propel, Zend Framework
• Python
• Ruby
• Smalltalk
  • Oracle TOPLink

Pro's and Con's

• ORM often reduces the lines of code needed to perform a task if you compare it with the common method of writing the queries using the SQL-statements and written field-code mappings.
• The code is written using a high abstraction of what is really happening under the (database)-hood.
• A database needs to be designed in an ordered and structured way. ORM hides this form the programmer.
• An alternative may be found in XML-databases using XML-techniques.
• An object as used in an OO-web-application may not represent the same storage object/table in a database.

See also

• List of ORM software, Wikipedia list of ORM software.
• Comparison of ORM software
• CORBA, The old one still exists!
• Object database, wikipedia description
• Object persisence, Object storage
• Java DataObjects