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

Explain the terms data warehousing and data mining, Question: i) Explai...

Question: i) Explain the terms data warehousing and data mining. ii) Discuss the importance of the following security principles that a digital firm should amongst others, n

MULTI-LIST FILE ORGANIZATION, sir, could anybody help me in getting complet...

sir, could anybody help me in getting complete information about the mentioned topic

Managing Data in Databases, Answer SQL Queries to extract data from data ta...

Answer SQL Queries to extract data from data tables and questions on mapping conceptual data models into relational data model.

What is recovery?, What Is Recovery?  During the life of a transaction, ...

What Is Recovery?  During the life of a transaction, i.e., a after the start of a transaction but before the transaction commits, various changes may be made in a database state

Describe sequential file organization, Describe sequential file organizatio...

Describe sequential file organization.  Explain the rules for (i)  Inserting a new record. (ii)  Deleting an existing record.          Ans:A sequential f

Define null value, Define NULL value NULL value NULL means something is...

Define NULL value NULL value NULL means something is unknown. It does NOT mean null (the digit 0). Null is as well employed as attribute value for a particular entity in which

Nested query, what is correlation in nested query

what is correlation in nested query

Prove that a relation which is 4nf must be bcnf, Prove that a relation whic...

Prove that a relation which is 4NF must be BCNF.   Ans Let R be in 4NF.  Suppose it is not in BCNF.  Hence, there exists an FD X→Y in R such that x is not a super key. Although

What do you understand by a view, What do you understand by a view? What do...

What do you understand by a view? What does WITH CHECK OPTION clause for a view do? - A view is a virtual table which comprises fields from one or more real tables. - It is

What are the concurrency issues, Concurrency issues Data integrity...

Concurrency issues Data integrity: Threads accessing same object need to be synchronized, such as: banking account. Deadlock: One or more threads in system are perman

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