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

Example of ancestry database , Ancestry database records information about ...

Ancestry database records information about family trees . Following information is recorded about each person: FIRSTNAME first name SURNAME surname MNAME maiden name (if

Digital, #floating point representation is used to store

#floating point representation is used to store

Explain different types of keys and relational model., Relational Model: T...

Relational Model: The relational model uses a collection of tables to represent both data and the relationships among those data. Each table has multiple columns and each column h

Which is a legal expression in sql, Which is a legal expression in SQL? ...

Which is a legal expression in SQL? SELECT NAME FROM EMPLOYEE is a legal expression in SQL.

Define the concept of object diagram, Define the concept of Object Diagram ...

Define the concept of Object Diagram An object diagram shows a set of the objects and their relationships with each other at a point of time. In a static view, object diagram

What is hashing file organization, What is hashing file organization? ...

What is hashing file organization? In the hashing file organization, a hash function is computed on some attribute of every record. The result of the hash function specify in

What are the parts of sql language, What are the parts of SQL language? ...

What are the parts of SQL language? The SQL language has various parts: data - definitition language  Data manipulation language  View definition  Transaction contr

HIT, Meaningful use refers to the use of certified EHR technology to "enhan...

Meaningful use refers to the use of certified EHR technology to "enhance quality, efficiency, and reduce health disparities

Nested queries, Nested Queries Let us see some more complex queries in ...

Nested Queries Let us see some more complex queries in this section. Sub-queries: Some of the basic concerns of sub-queries are: A sub-query is a SELECT statemen

A database administrator'', A database administrator''s responsibilities an...

A database administrator''s responsibilities and data contents

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