Unit database integrity, Database Management System

Relations create the database. They must satisfy various properties, like no duplicate tuples, no ordering of tuples, and atomic attributes, etc. Relations that satisfy these basic needs may still have some undesirable characteristics such as data redundancy, and anomalies.

What are these undesirable characteristics and how can we eliminate them from the database system? This part is an attempt to answer this question. Though, please note that most of these undesirable properties do not arise if the database modelling has been carried out very carefully using some method like the Entity-Relationship Model. It is still important to use the methods in this unit to check the database that has been acquired and ensure that no mistakes have been made in modeling.

The central thought in these discussions is the concept of Database integrity, the notion of functional dependency, which rely on understanding the semantics of the data and which deals with what information in a relation is dependent on what other information in the relation. Our prime objective in this section is to describe the concept of data integrity, functional dependence and then describes normal forms using functional dependencies and using other types of data dependencies.

OBJECTIVES

After reading this section you should be able to

  • Explain the concept of entity integrity;
  • Define relational database referential integrity constraints;
  • Explain the concept of functional dependency, and
  • show how to use the dependencies information to decompose relations; whenever essential to obtain relations that have the desirable properties that we want without losing any of the information in the original relations.

 

Posted Date: 3/6/2013 6:29:08 AM | Location : United States







Related Discussions:- Unit database integrity, Assignment Help, Ask Question on Unit database integrity, Get Answer, Expert's Help, Unit database integrity Discussions

Write discussion on Unit database integrity
Your posts are moderated
Related Questions
What are the differences among MySQL_fetch_array(), MySQL_fetch_object(), MySQL_fetch_row()? Mysql_fetch_object returns the result from the database like objects while mysql

What is Data Storage? The storage structures and access methods used by database system are specified by a set of explanation in a special type of DDL called data storage-defin

What is DML compiler? DML Compiler: Translates DML statements in a query language within low level instructions understandable through the query evaluation engine. Attempts to

what do you mean by consistency in rdbms?

Discuss how the one-to-one associations have to be implemented. Some of properties of associations can be implemented directly by providing suitable declarations of the data me

Explain the Natural join Natural join is a binary operator which is written as (R* S) in which R and S are relations. The effect of the natural join is the set of all combinati

Explain what is Aggregation? Aggregation: Aggregation is an significant concept in database design whereas composite objects could be modelled during the design of database a

Explain the Difference between DROP and DELETE DELETE deletes one or more than one tuples of a particular relation from the database. DROP is employed to remove a table from th

What are the advantages of object oriented databases in comparison with others? Why it is still not widely used? Object oriented designs are coherent, efficient and less prone

Question : Mr. Smith Harry has a car manufacturing company which has recently integrated management information system. He wishes to obtain more information on ethics and socia