An object-relational database (ORD), or object-relational database management system (ORDBMS), is a database management system
Database management system
A database management system is a software package with computer programs that control the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications by database administrators and other specialists. A database is an integrated...
A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system . Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself...
, but with an object-oriented database model: objects, classes and inheritance are directly supported in database schema
Database schema
A database schema of a database system is its structure described in a formal language supported by the database management system and refers to the organization of data to create a blueprint of how a database will be constructed...
Query languages are computer languages used to make queries into databases and information systems.Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages...
. In addition, it supports extension of the data model
Data model
A data model in software engineering is an abstract model, that documents and organizes the business data for communication between team members and is used as a plan for developing applications, specifically how data is stored and accessed....
In computer programming, a data type is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, that determines the possible values for that type; the operations that can be done on values of that type; the meaning of the data; and the way values of...
In object-oriented programming, a method is a subroutine associated with a class. Methods define the behavior to be exhibited by instances of the associated class at program run time...
s.
An object-relational database can be said to provide a middle ground between relational databases and object-oriented databases (OODBMS). In object-relational databases, the approach is essentially that of relational databases: the data resides in the database and is manipulated collectively with queries in a query language; at the other extreme are OODBMSes in which the database is essentially a persistent object store for software written in an object-oriented programming language
Object-oriented programming language
This is a list of object-oriented programming programming languages.-Languages with object-oriented features:*ABAP*Ada 95*AmigaE*BETA*Blue*Boo*C++*C#*COBOL*Cobra*ColdFusion*Common Lisp*COOL*CorbaScript*Clarion*CLU*Curl*D*Dylan*E*Eiffel...
, with a programming API for storing and retrieving objects, and little or no specific support for querying.
Overview
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
Java (programming language)
Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
Visual Basic .NET , is an object-oriented computer programming language that can be viewed as an evolution of the classic Visual Basic , which is implemented on the .NET Framework...
or 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)
Object-relational mapping
Object-relational mapping in computer software is a programming technique for converting data between incompatible type systems in object-oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language...
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.
This is a list of object-oriented programming programming languages.-Languages with object-oriented features:*ABAP*Ada 95*AmigaE*BETA*Blue*Boo*C++*C#*COBOL*Cobra*ColdFusion*Common Lisp*COOL*CorbaScript*Clarion*CLU*Curl*D*Dylan*E*Eiffel...
. So, the characteristic properties of ORDBMS, in comparison with RDBMS, 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 additional 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 have to be storable and transportable for database processing, therefore they usually are named as persistent objects. Inside a database, all the relations with a persistent program object are relations with its object identifier (OID)
Object identifier
In computing, an object identifier or OID is an identifier used to name an object . Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard. Successive numbers of the nodes, starting at the root of the tree, identify each...
Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...
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
Polymorphism in object-oriented programming
Subtype polymorphism, almost universally called just polymorphism in the context of object-oriented programming, is the ability to create a variable, a function, or an object that has more than one form. The word derives from the Greek "πολυμορφισμός" meaning "having multiple forms"...
principle, which briefly is defined as "one interface, many implementations". Other OOP principles, inheritance
Inheritance (object-oriented programming)
In object-oriented programming , inheritance is a way to reuse code of existing objects, establish a subtype from an existing object, or both, depending upon programming language support...
In a programming language encapsulation is used to refer to one of two related but distinct notions, and sometimes to the combination thereof:* A language mechanism for restricting access to some of the object's components....
are related both, with methods and attributes. Method inheritance is included in type inheritance. Encapsulation in OOP is a visibility degree declared, for example, through the PUBLIC, PRIVATE and PROTECTED modifiers.
History
Object-relational database management systems grew out of research that occurred in the early 1990s. That research extended existing relational database concepts by adding object
Object (computer science)
In computer science, an object is any entity that can be manipulated by the commands of a programming language, such as a value, variable, function, or data structure...
concepts. The researchers aimed to retain a declarative query-language based on predicate calculus
Predicate logic
In mathematical logic, predicate logic is the generic term for symbolic formal systems like first-order logic, second-order logic, many-sorted logic or infinitary logic. This formal system is distinguished from other systems in that its formulae contain variables which can be quantified...
as a central component of the architecture. Probably the most notable research project, Postgres (UC Berkeley), spawned two products tracing their lineage to that research: Illustra
Illustra
Illustra was a commercialized version of the Postgres object-relational database management system sold by Illustra Information Technologies, a company formed by Michael Stonebraker and Gary Morgenthaler and several of Michael Stonebraker's current and former students including: Wei Hong, Jeff...
PostgreSQL, often simply Postgres, is an object-relational database management system available for many platforms including Linux, FreeBSD, Solaris, MS Windows and Mac OS X. It is released under the PostgreSQL License, which is an MIT-style license, and is thus free and open source software...
.
In the mid-1990s, early commercial products appeared. These included Illustra (Illustra Information Systems, acquired by Informix Software which was in turn acquired by IBM), Omniscience (Omniscience Corporation, acquired by Oracle Corporation
Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation that specializes in developing and marketing hardware systems and enterprise software products – particularly database management systems...
and became the original Oracle Lite), and UniSQL (UniSQL, Inc., acquired by KCOMS). Ukrainian developer Ruslan Zasukhin, founder of Paradigma Software, Inc.
Paradigma Software
Paradigma Software is the developer of database-related products for business and developers based on its original database technology Valentina.- Products :Paradigma Software products include:...
, developed and shipped the first version of Valentina database in the mid-1990s as a C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
A software development kit is typically a set of software development tools that allows for the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar platform.It may be something as simple...
. By the next decade, PostgreSQL had become a commercially viable database and is the basis for several products today which maintain its ORDBMS features.
Computer scientists came to refer to these products as "object-relational database management systems" or ORDBMSs.
Many of the ideas of early object-relational database efforts have largely become incorporated into SQL:1999
SQL
SQL is a programming language designed for managing data in relational database management systems ....
. In fact, any product that adheres to the object-oriented aspects of SQL:1999 could be described as an object-relational database management product. For example, IBM's DB2
IBM DB2
The IBM DB2 Enterprise Server Edition is a relational model database server developed by IBM. It primarily runs on Unix , Linux, IBM i , z/OS and Windows servers. DB2 also powers the different IBM InfoSphere Warehouse editions...
Microsoft SQL Server is a relational database server, developed by Microsoft: It is a software product whose primary function is to store and retrieve data as requested by other software applications, be it those on the same computer or those running on another computer across a network...
, make claims to support this technology and do so with varying degrees of success.
SQL is a programming language designed for managing data in relational database management systems ....
statements such as these:
CREATE TABLE Customers (
Id CHAR(12) NOT NULL PRIMARY KEY,
Surname VARCHAR(32) NOT NULL,
FirstName VARCHAR(32) NOT NULL,
DOB DATE NOT NULL
);
SELECT InitCap(Surname) || ', ' || InitCap(FirstName)
FROM Customers
WHERE Month(DOB) = Month(getdate)
AND Day(DOB) = Day(getdate)
Most SQL databases allow the crafting of custom functions, which would allow the query to appear as:
SELECT Formal(Id)
FROM Customers
WHERE Birthday(Id) = Today
In an object-relational database, one might see something like this, with user-defined data-types and expressions such as BirthDay:
CREATE TABLE Customers (
Id Cust_Id NOT NULL PRIMARY KEY,
Name PersonName NOT NULL,
DOB DATE NOT NULL
);
SELECT Formal( C.Id )
FROM Customers C
WHERE BirthDay ( C.DOB ) = TODAY;
The object-relational model can offer another advantage in that the database can make use of the relationships between data to easily collect related records. In an address book
Address book
An address book or a name and address book is a book or a database used for storing entries called contacts. Each contact entry usually consists of a few standard fields...
application, an additional table would be added to the ones above to hold zero or more addresses for each user. Using a traditional RDBMS, collecting information for both the user and their address requires a "join":
SELECT InitCap(C.Surname) || ', ' || InitCap(C.FirstName), A.city
FROM Customers C join Addresses A ON A.Cust_Id=C.Id -- the join
WHERE A.city="New York"
The same query in an object-relational database appears more simply:
SELECT Formal( C.Name )
FROM Customers C
WHERE C.address.city="New York" -- the linkage is 'understood' by the ORDB
An object database is a database management system in which information is represented in the form of objects as used in object-oriented programming...
Object-relational mapping in computer software is a programming technique for converting data between incompatible type systems in object-oriented programming languages. This creates, in effect, a "virtual object database" that can be used from within the programming language...
The relational model for database management is a database model based on first-order predicate logic, first formulated and proposed in 1969 by Edgar F...
Linq is a word-based card game from Endless Games, introduced at the American International Toy Fair in 2005.Game play requires at least four players, two of whom are dealt cards with the same word, while the others receive blanks. The goal is to gain points by correctly naming the players with...
ADO.NET Entity Framework is an object-relational mapping framework for the .NET Framework.-Overview:ADO.NET Entity Framework abstracts the relational schema of the data that is stored in a database and presents its conceptual schema to the application...
The object-relational impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management system is being used by a program written in an object-oriented programming language or style; particularly when objects or class definitions...
context.
The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.
An object-relational database can be said to provide a middle ground between relational databases and object-oriented databases (OODBMS). In object-relational databases, the approach is essentially that of relational databases: the data resides in the database and is manipulated collectively with queries in a query language; at the other extreme are OODBMSes in which the database is essentially a persistent object store for software written in an object-oriented programming language