Editing Object–relational database (section)

== Overview ==
The basic need of object–relational database arises from the fact that both Relational and Object database have their individual advantages and drawbacks. The isomorphism of the relational database system with a mathematical relation allows it to exploit many useful techniques and theorems from set theory. But these types of databases are not optimal for certain kinds of applications. An object oriented database model allows containers like sets and lists, arbitrary user-defined datatypes as well as nested objects. This brings commonality between the application type systems and database type systems which removes any issue of impedance mismatch. But object databases, unlike relational do not provide any mathematical base for their deep analysis.<ref name="fstajano">{{Citation |url=https://www.cl.cam.ac.uk/~fms27/db/tr-98-2.pdf |title=A Gentle Introduction to Relational and Object Oriented Databases |author=Frank Stajano |year=1995}}</ref><ref name="namansg">{{Citation |url=http://home.iitk.ac.in/~namansg/cs300/3C.pdf |title=Technical Paper Review |author=Naman Sogani |year=2015 |access-date=2015-10-05 |archive-url=https://web.archive.org/web/20160304190615/http://home.iitk.ac.in/~namansg/cs300/3C.pdf |archive-date=2016-03-04 |url-status=dead}}</ref>

The basic goal for the object–relational database is to bridge the gap between relational databases and the [[object-oriented modeling]] techniques used in programming languages such as [[Java (programming language)|Java]], [[C++]], [[Visual Basic (.NET)]] or [[C Sharp (programming language)|C#]]. However, a more popular alternative for achieving such a bridge is to use a standard relational database systems with some form of [[object–relational mapping]] (ORM) software. Whereas traditional [[RDBMS]] or SQL-DBMS products focused on the efficient management of data drawn from a limited set of data-types (defined by the relevant language standards), an object–relational DBMS allows software developers to integrate their own types and the methods that apply to them into the DBMS.

The ORDBMS (like [[ODBMS]] or [[OODBMS]]) is integrated with an [[object-oriented programming]] language. The characteristic properties of ORDBMS are 1) complex data, 2) type inheritance, and 3) object behavior. ''Complex data'' creation in most SQL ORDBMSs is based on preliminary schema definition via the [[user-defined type]] (UDT). Hierarchy within structured complex data offers an added property, ''type inheritance''. That is, a structured type can have subtypes that reuse all of its attributes and contain additional attributes specific to the subtype. Another advantage, the ''object behavior'', is related with access to the program objects. Such program objects must be storable and transportable for database processing, therefore they usually are named as [[persistent object]]s. Inside a database, all the relations with a persistent program object are relations with its [[object identifier]] (OID). All of these points can be addressed in a proper relational system, although the SQL standard and its implementations impose arbitrary restrictions and additional complexity<ref>{{Citation |last1=Date |first1=Christopher ‘Chris’ J. |last2=Darwen |first2=Hugh |author2-link=Hugh Darwen |title=The Third Manifesto}}</ref>{{Rp |needed=yes|date=March 2012}}

In [[object-oriented programming]] (OOP), object behavior is described through the methods (object functions). The methods denoted by one name are distinguished by the type of their parameters and type of objects for which they attached ([[method signature]]). The OOP languages call this the [[Polymorphism (computer science)|polymorphism]] principle, which briefly is defined as "one interface, many implementations". Other OOP principles, [[Inheritance (object-oriented programming)|inheritance]] and [[Encapsulation (object-oriented programming)|encapsulation]], are related both to methods and attributes. Method inheritance is included in type inheritance. Encapsulation in OOP is a visibility degree declared, for example, through the <code>public</code>, <code>private</code> and <code>protected</code> [[access modifiers]].