Relational Database vs Object Oriented Database

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Institute of graduate studies &research Information technology department

Database systems
Report on:
(Comparison between Relational database & object oriented database) By: Mohammed Hussein Mahmoud Mustafa khedr

To: Dr. Saad Darwish

Introduction
A database is a means of storing information in such a way that information can be retrieved from it. Thus a database is typically a repository for heterogeneous but interrelated pieces of information. Often a database contains more than one table. Codebooks and dictionaries can also be considered as tables. A dictionary is a reference book on any subject, the items of which are arranged in alphabetical order. Codebook is a list of replacements for words or phrases in the original message. A code is a system for hiding the meaning of a message by replacing each word or phrase in the original message with another character or set of characters. The list of replacements is contained in a codebook. An alternative definition of a code is any form of encryption which has no builtin flexibility, i.e. there is only one key, namely the codebook. Databases contain organized data. A database can be as simple as a flat file (a single computer file with data usually in a tabular form) containing names and telephone numbers of one’s friends, or as elaborate as the worldwide reservation system of a major airline. There are many ways to approach the design of a database and tables. The database layout is the most important part of an information system. The more design and thought put into a database, the better the database will be in the long run. We should gather information about the user’s requirement, data objects, and data definitions before creating a database layout. Traditionally, there are four different DBMS data models: the hierarchical data model, the network data model, the relational data model, and the objectoriented data model.

These four data models at the same time signifies the historical developments within DBMS technology, as the hierarchical is the oldest DBMS data model, and the object-oriented being the newest DBMS data model.

Relational database:In the relational data model, information is organized in relations (twodimensional tables). Each relation contains a set of tuples (records). Each tuple contain a number of fields. A field may Contain a simple value (fixed or variable size) from some domain (e.g. integer, real, text, etc.).

Example of a Relational Data Model

The relational data model is based on a mathematical foundation, called relational algebra. This mathematical foundation is the cornerstone to some of the very attractive. Properties of relational databases, since it first of all offers data independence, and offers a mathematical framework for many of the optimizations possible in relational databases (e.g. query optimization). Relational modeling focuses on the information in the system not on the behavior. The modeling dimension consists of translations between the human knowledge and the database model.

All of this is accomplished in the Relational DBMS through well defined terms like relation, tuple, domain, and database. RELATION: - A relation is a truth predicate. It defines what attributes are involved in the predicate and what the meaning of the predicate is. Frequently the meaning of the relation is not represented explicitly, but this is a very significant source for human error in using the database system. An example of a relation is: Person: {SSN#, Name, City} There exists a person with social security number SSN#, who has the name Name, and lives in a city named City. ATTRIBUTE: - An attribute identifies a name that participates in the relation and specifies the domain from which values of the attribute must come. In the above relation, Name is an attribute defined over the String domain. The above relation should explicitly identify the domains for each attribute: Person: {SSN#: SSN, Name : String, City :...
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