Explain entity integrity and referential integrity rules, Database Management System

Assignment Help:

Explain entity integrity and referential integrity rules within relational model. Show how these are realized in SQL?

Entity Integrity Rule - No primary key value could be null.

Referential Integrity Rule - In referential integrity, it is ensured in which a value which appears in one relation for a given set of attributes also appears for a certain set of attributes within another relation.

In SQL, entity integrity and referential integrity rules are implemented as constraints on the relation known as primary key constraint or reference key constraint corresponding. These constraints can be specified along with relation at the time of creation of the relations or after the creation of the relations through altering the definition of the relations. For instance:

CREATE TABLE DEPT

(DEPTNO NUMBER PRIMARY KEY,

DNAME VARCHAR2(15));

CREATE TABLE EMP

(EMPNO NUMBER PRIMARY KEY,

 20

 ENAME VARCHAR2(15),

JOB VARCHAR2(10),

DEPTNO NUMBER REFERENCES DEPT(DEPTNO));


Related Discussions:- Explain entity integrity and referential integrity rules

What are the various forms of data transparency, What are the various forms...

What are the various forms of data transparency? a) fragmentation transparency b) replication transparency c) location transparency

Functional Dependencies, What exactly is the concept of Functional Dependen...

What exactly is the concept of Functional Dependencies? And how do we associate this concept with the logic of Super-keys, Candidate Keys, etc? Given Relation R(A,B,C,D,E) with de

Parallelism of transaction execution-data fragmentation, Parallelism of tra...

Parallelism of transaction execution: A transaction can be divided into various sub-queries that can operate on fragments in parallel. This enhances the degree of concurrency in t

Explain the project-join normal form, Explain the Project-Join normal form ...

Explain the Project-Join normal form A relation R is in PJNF along with respect to a set of functional dependencies D if for all join dependencies of the outline *(R 1 , R 2 ,

Explain th process to avoid re-computation, Saving Derived Attributes to Av...

Saving Derived Attributes to Avoid Re-computation Data that is derived from other data should be stored in the computed form to avoid re-computation. For this, we could define

Explain the term - control as concurrent tasks, Explain the term - Control ...

Explain the term - Control as Concurrent Tasks As we know, any object can be implemented as a task in programming language or operating system. This is the most general approa

What is disadvantage of multiple inheritances, What is disadvantage of mult...

What is disadvantage of multiple inheritances? There is potential ambiguity if the similar variable or method can be inherited from more than one superclass.eg: student class m

3NF, Winfield is a small city with a population of 22,000 with buses serves...

Winfield is a small city with a population of 22,000 with buses serves three routes in Winfield and neighboring areas. As the city’s IT director, you have been asked to set up an i

Entity set or entity type, A collection of a same kind of entities is known...

A collection of a same kind of entities is known as an Entity Set or entity type. Example: For the COLLEGE database defines earlier objects of concern are Students, Faculty,

The first normal form (1nf), The First Normal Form (1NF) Let us first d...

The First Normal Form (1NF) Let us first describe 1NF: Definition: A relation (table) is in 1NF if 1.      There are no duplicate tuples or rows in the relation. 2.

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