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

Normalization, Process of normalization is the integral part of designing a...

Process of normalization is the integral part of designing a database. Justify this statement with suitable database design

Define seek time, Define seek time. The time for repositioning the arm ...

Define seek time. The time for repositioning the arm is known as the seek time and it enhances with the distance that the arm is known as the seek time.

Explain disadvantages of a dbms, Question : (a) Database Management Sy...

Question : (a) Database Management Systems (DBMS) is the foundation of business intelligence. Explain the following concepts related to DBMS: (i) Entity Relationship Diagr

Modelling and normalisation, Task Part A. Create an ERD from a business pro...

Task Part A. Create an ERD from a business problem. (50 marks) Read the following problem and complete the tasks listed below. THE ABS Blood Bank Australian Blood Services (ABS) i

How is concurrency identified, How is concurrency identified? Concurren...

How is concurrency identified? Concurrency in objects can be identified by the way they alter their state. Current objects can change their state independently. Aggregation imp

Dbms built for online transaction processing, Problem: A DBMS built for...

Problem: A DBMS built for Online Transaction Processing (OLTP) is usually regarded as unsuitable for data warehousing. Each system is designed with a different set of requireme

Economics, Economics: It is now usually accepted that it costs less to make...

Economics: It is now usually accepted that it costs less to make a system of smaller computers with the equivalent power of a one large computer. It is more cost-effective to get s

Define query processing, Define Query Processing Query processing is th...

Define Query Processing Query processing is the process of selecting the best plan or strategy to be employed in responding to a database request. The plan is then executed to

Which is the properties of entities, Which is the properties of entities? ...

Which is the properties of entities? Attributes is the properties of entities.

Determine the types of methods for retrieving rows in python, Describe the ...

Describe the two types of methods for retrieving rows in Python? Fetchone()- Returns the next row as a sequence Fetch all()- Returns the entire result set like a strin

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