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

Describe about use case and external case in dfd, Describe about Use Case a...

Describe about Use Case and external case in DFD The processes are transformed those into the Use Case and external case in DFD has same characteristics which of an actor in O

What is a cascading update, What is a cascading update? Referential int...

What is a cascading update? Referential integrity constraints needs that foreign key values in one table correspond to primary key values in another. If the value of the primar

What is inheritance, What is inheritance? Define it in detail?  Inheri...

What is inheritance? Define it in detail?  Inheritance Inheritance can be at the levels of types, or at the level of tables we first consider inheritance of types, then i

Differance between open addressing and chaining collision, Differance betwe...

Differance between Open addressing and chaining for collision resolution ? In open addressing , proceeding from the occupied position specified by hash address the program che

Write short notes on domain relational calculus, Write short notes on domai...

Write short notes on domain relational calculus   The domain relational calculus uses domain variables that take on values from an attribute domain rather than values for whole

Write short notes on domain relational calculus, Write short notes on domai...

Write short notes on domain relational calculus The domain relational calculus uses domain variables that take on values from an attribute domain rather than values for whole t

Access data using logical database, If one requires to access data using...

If one requires to access data using Logical Database , the use of events is unavoidable. Yes, if someone wants to access data using Logical database then the use of events

Normalization-e-r mapping , Normalize the following table upto and includin...

Normalize the following table upto and including the 3NF. Submit a 1 page printout of only the final set of normalized tables in Data Architect. Just use Data Architect to do the t

Data manipulation language, Data Manipulation Language Data manipulatio...

Data Manipulation Language Data manipulation language (DML) describes a set of commands that are used to query and change data within existing schema objects. In this case comm

Describe the algorithm to draw the dependency graph, Describe the algorithm...

Describe the algorithm to draw the dependency graph?   Ans: Algorithm to draw Precedence Graph is like this: a.  For every transaction T i participating in schedule S, make

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