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

Describe how you can simplify operations, Describe how you can simplify Ope...

Describe how you can simplify Operations. To simplify operation, one should use inheritance, where possible to use, to reduce the quantity of distinct operations. Introduce new

What is conceptual model, What is conceptual model ? A conceptual model...

What is conceptual model ? A conceptual model is a independent of both hardware and software.

What are the requirements of algorithm designer, What are the Requirements ...

What are the Requirements of algorithm designer Algorithm designer should: i) Select proper algorithm so as to minimize implementation cost ii) Find most appropriate d

Explain the difference between drop and delete, Explain the Difference betw...

Explain the Difference between DROP and DELETE DELETE deletes one or more than one tuples of a particular relation from the database. DROP is employed to remove a table from th

What is functional dependency, A Functional dependency is described by ...

A Functional dependency is described by X Y between two groups of attributes Y and X that are subsets of R specifies a constraint on the possible tuple that can make a relation

What are the strategies of implementation of the statecharts, What are the ...

What are the different strategies of implementation of the Statecharts?  There are two strategies for implementation of state charts: i)   Basic Implementation Strategy

Explain thomas write rule, Explain Thomas' Write rule.  Show how it is diff...

Explain Thomas' Write rule.  Show how it is different from timestamp ordering protol Ans: In timestamp-based concurrency control the thomas Write rule is a rule. Given a Timest

What is advantage of two-way association, What is advantage of two-way asso...

What is advantage of two-way association? Two-way association advantages are following: a) Independent of the classes. b) Useful for existing predefined classes that are

Where does view definition stored, Where does view definition stored? ...

Where does view definition stored? A view definition is permanently stored as part of the database.

Hierarchical data representation model, Examples:- Hierarchical Model: I...

Examples:- Hierarchical Model: It tells data as and relationships by hierarchy of data values. Figure illustrates an example of hierarchical model. Now a day's these models are

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