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 in brief about object oriented design, Describe about Object orien...

Describe about Object oriented design Object oriented design is concerned with developing an object oriented model of a software system to implement known requirements. Many OO

Er schema, Consider entity type Employee with attributes empNumber (this is...

Consider entity type Employee with attributes empNumber (this is unique), empName, and the year when he/she was hired. An employee can either be a technical employee, a marketing e

Determine the object-oriented design process, An object-oriented design pro...

An object-oriented design process  1. Define the context and modes 2. Designs the system architecture 3. Identifies the principal system objects 4. Identifies concurrency in

Give expression in tuple calculus and domain calculus, Consider the subsequ...

Consider the subsequent relation schemes:  Project (Project#, Project_name, chief_architect)  Employee (Emp#, Empname)  Assigned_To (Project#, Emp#)  Give expression i

Entity set that does not have sufficient attributes known as, An entity set...

An entity set that does not have sufficient attributes to form a primary key is called? An entity set that doesn't have sufficient attribute to form a primary key is known as w

What are the drawbacks of file oriented system in details, What are the dr...

What are the drawbacks of File Oriented System in details?

Give the levels of data abstraction, Give the levels of data abstraction? ...

Give the levels of data abstraction? There are three levels of Data Abstraction a) Physical level b) logical level c) view level

Explain the concept of deadlock, Question: In a multi-user database env...

Question: In a multi-user database environment, locking mechanisms can be used to solve the three basic problems of concurrency. On the other hand, however, locking may also le

Dealing with constraints violation, If the deletion violates referential in...

If the deletion violates referential integrity constraint, then three alternatives are available: Default option: - refuse the deletion. It is the job of the DBMS to describ

Define hot swapping, Define hot swapping? Hot swapping permits the remo...

Define hot swapping? Hot swapping permits the removal of faulty disks and changes it by new ones without turning power off. Hot swapping decreases the mean time to repair.

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