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

Two phase locking (2pl), Two Phase Locking (2PL) The two-phase locking ...

Two Phase Locking (2PL) The two-phase locking protocol having of two phases: Phase 1 : The lock acquisition phase : If a transaction T needs to read an object, it wants to

Goals, what are the purposes of dbms in details

what are the purposes of dbms in details

Database application and creation, Create Relational Database Model (RDM) f...

Create Relational Database Model (RDM) for Sailing bed and breakfast club Table_Name( attribute_1, attribute_2, attribute_3, ? ,attribute_x) Primary Key ( attribute_1, attribute_2)

Delete - referential integrity, During the deletion of a tuple two cases ca...

During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in

Icloud based storage, Advantages and disadvantages of icloud based storage

Advantages and disadvantages of icloud based storage

Explain transaction, What is transaction? Collections of operations tha...

What is transaction? Collections of operations that form a single logical unit of work are known as transactions.

What are the advantages of relational data model, What are the advantages o...

What are the advantages of relational data model? Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer

Entity - relation modeling and transformation, Represent the following scen...

Represent the following scenarios with E-R diagrams drawn using the ER Assistant software. The diagrams should indicate cardinality and optionality of relationships. Transform each

Explain about foreign key, What is Foreign Key Foreign Key: Sometimes...

What is Foreign Key Foreign Key: Sometimes we may have to work with an attribute that does not have a primary key of its own. To recognize its rows, we have to use the primar

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