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

Hashed file organisation, Hashed File Organisation Hashing is the most ...

Hashed File Organisation Hashing is the most common form of purely random access to a database or file. It is also used to access columns that do not have an index as an optimi

Design an entity relation model, Funky Festivals Specification Funky Fe...

Funky Festivals Specification Funky Festivals organise music festivals which take place at various venues throughout the UK.  A venue needs to be booked before a Festival can t

What do you mean by persistence, What do you mean by persistence? How you w...

What do you mean by persistence? How you will make your data persistent? Persistent data is the data, which has a longer lifetime than program which has created it. Enabling th

What are the objectives of advance object design, What are the Objectives o...

What are the Objectives of Advance object design After this unit, you shall be able to: combine three OOAD models to obtain operations on the classes; develop algo

Drop table command, DROP TABLE Command: When an existing object is not ...

DROP TABLE Command: When an existing object is not needed for further use, it is always better to eliminate it from the database. To remove the existing object from the databas

What is omr, What is OMR? OMR (Optical Mark Recognition) is the transla...

What is OMR? OMR (Optical Mark Recognition) is the translation of marks - or the absence of marks - but not the shape of the mark on forms that have small circles ("also called

Draw an er diagram with primary key for a farm, Draw an ER diagram that rep...

Draw an ER diagram that represents the information described below. Show all entity sets, relationship sets, primary keys, and the mapping cardinality of the relationship sets.

Entity relationship diagram, The Enhanced Entity Relationship Diagram (ERD)...

The Enhanced Entity Relationship Diagram (ERD) produced with a drawing or case tool. Your EERD must use a ''standard'' notation style such as Crows Foot or Chen. Please note that t

Queries, Write a query that display ename annual salary and comm from emp t...

Write a query that display ename annual salary and comm from emp table

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