Unit database integrity, Database Management System

Assignment Help:

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.

 


Related Discussions:- Unit database integrity

#cursor, #what is cursor its uses ? Explain it

#what is cursor its uses ? Explain it

Find out the names of all employees from database, Find out the names of al...

Find out the names of all employees who work for first Bank Corporation from database. SELECT EMPLOYEE_NAME FROM WORKS WHERE COMPANYNAME = ‘First Bank Corporation';

What is a view, What is a view? A view is a logical view on one or more...

What is a view? A view is a logical view on one or more tables.  A view on one or more tables i.e., the data from a view is not actually physically kept instead being derived f

Explain the difference between drop and delete, Explain the Difference betw...

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 failures of controlling events between objects, What are the f...

What are the failures of Controlling Events Between Objects  Failure Unintentional termination of system. Several possible causes: failure of system hardware, o

State the objectives of object design, Determine the OBJECTIVES of  object ...

Determine the OBJECTIVES of  object design After passing through this unit, you should be able to: describe and apply concept of generalisation; understand and appl

Mention the several levels in security measures, Mention the several levels...

Mention the several levels in security measures. A) Database system B) Operating system C) Network D) Physical Human

Explain the three data anomalies, What are the three data anomalies that ar...

What are the three data anomalies that are similarly to take place as a result of data redundancy?  Can data redundancy be completely eliminated in database approach?  Why or why n

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd