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

Develop a cards website, Project Description: I want to build a card pla...

Project Description: I want to build a card playing Website. The user should be able to 1. Login. 2. Have profile access. 3. Put money into the site. 4. Selects t

Requirements for your cache simulator, Using your cache simulator and using...

Using your cache simulator and using smalltex.din as your memory trace determine the total miss rate, compulsory miss rate, capacity miss rate, and conflict miss rate for the follo

Explain difference between volatile, Explain the difference between the thr...

Explain the difference between the three storage types - volatile, non volatile and stable.             Ans: Volatile storage: if storage media loses data while power goes off,

Write a short note on built in function in qbe, Write a short note on built...

Write a short note on built in function in QBE? Built in function in QBE: QBE involves various built in functions like AVG, MAX,MIN,SUM and CNT. We must prefix these operator

Describe the relational model, a) Distinguish between ‘database' and ‘Data...

a) Distinguish between ‘database' and ‘Database Management Systems (DBMS)'. b) List and briefly describe five potential benefits of the database approach compared to conventio

Er digrams, what is er digram given that example of hospital,bank and libra...

what is er digram given that example of hospital,bank and library er digram.

What are the two aspect to the implementation of association, What are the ...

What are the two distinct aspects to the implementation of associations? i) It is required to define data declarations which will enable details of actual links to be stored. I

What are the types of indices, Normal 0 false false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

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