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

What is alternate key, What is Alternate Key Alternate Key: This is t...

What is Alternate Key Alternate Key: This is the candidate key which is not taken as the primary key of the table. They are named so because although not the primary key, the

Relation schema for student, Example RELATION SCHEMA for STUDENT: STU...

Example RELATION SCHEMA for STUDENT: STUDENT (Roll No: string, name: string, login: string, age: integer) RELATION INSTANCE

What is aggregate function, What is aggregate function? Briefly describe it...

What is aggregate function? Briefly describe it? Aggregate functions are functions that take a collection of values as input and return a one value. SQL offers 5 built-in aggre

Creating views with check option-data control, Creating views with check op...

Creating views with check option : This option limits those updates of data values that cause records to go off the view. The following instance tells this in more detail: Examp

What are the advantages of embedded query language, What are the advantages...

What are the advantages of embedded query language? Give an example of an embedded SQL query. Embedded query language - SQL could be implemented within two ways. It can be us

ER DIAGRAM, draw ER diagram of student entity and course entity where attri...

draw ER diagram of student entity and course entity where attribute of student entity are student roll, student name, student phone and student address and attribute of course enti

Define single valued and multivalued attributes, Define single valued and m...

Define single valued and multivalued attributes.  Single valued attributes: attributes with a single value for a particular entity are known as single valued attributes.   M

List the reg-no of vehicles owned in relational algebra, Given the followin...

Given the following relations Vehicle (Reg_no, make, colour) Person(eno, name, address) Owner(eno, reg_no) Write expressions in the relational algebra to answer the following

Database Management System, Assume that you are responsible for selecting a...

Assume that you are responsible for selecting a new DBMS product for Sohar Hospital

Give an example of multiple inheritance, Give an example of multiple inheri...

Give an example of multiple inheritance.  One example of multiple inheritance is a committee for students affair which include faculty and administrative staff member.

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