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

Write query to select student from math department, Consider the table stud...

Consider the table student and list names of students in the departments other than maths and computer. SELECT std_name FRM student WHERE dept_name NOT IN (‘Maths','Computer);

Mapping, external and internal mapping with examples

external and internal mapping with examples

Determine bcnf-dcnf and key relation, (A) For the relation; CarSales (R...

(A) For the relation; CarSales (RegNo, BuyerName, Address, SalesPerson, Make, Model, Commission) The following functional dependences hold, RegNo _ID à Make, Model Reg

Determine the steps of path in association network, Determine the steps of ...

Determine the steps of path in association network You can analyse use of paths in association network in the following steps:  Examine every operation and see what asso

Modify - referential integrity, Update or Modify operation alters the exist...

Update or Modify operation alters the existing values. If these operations alter the value that is the foreign key also, the only check need is the similar as that of the Insert op

One-to-many relationship, For each 1: n relationship type R involving two e...

For each 1: n relationship type R involving two entities E1 and E2, we recognize the entity type (say E1) at the n-side of the relationship type R and contain primary key of the en

Differences between structured data and unstructured data, Explain the diff...

Explain the differences between structured data and unstructured data. Structured data are facts concerning objects and events. The most significant structured data are numeric

Log based recovery, Log based recovery: Let us first describe the term tran...

Log based recovery: Let us first describe the term transaction log in the context of DBMS. A transaction log is a record in DBMS that remains track of all the transactions of a dat

Mr.dattu, Define a job scheduling strategy that will meet business requirem...

Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pictori

What are the responsibility of file manager, What are the responsibility of...

What are the responsibility of File manager? File Manager : Manager allocation of space on disk storage and the data structures used to represent within stored on disk. It is a

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