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

Linked list, what is difference between circular inked lust and grunded lin...

what is difference between circular inked lust and grunded linked list

Write short notes on transaction state, Write short notes on transaction st...

Write short notes on transaction state? A transaction may not always complete its implementation successfully such a transaction is termed aborted A transaction must be in o

boyce codd normal form relations, Create centralized relational database u...

Create centralized relational database using bottom up method.   (a) Recognize a single un-normalized relation for the above scenario.          (b) Recognize the primary key for

Determine the strong and weak entity, Determine the Strong and Weak Entity ...

Determine the Strong and Weak Entity Based on the method of foreign key, there might be arise a situation when we have to relate an entity having a primary key of its own and a

Describe different steps of object-oriented design process, Describe differ...

Describe different steps of the object-oriented design process.  The broad steps of the object-oriented design process are: a. Define context and modes of use of the system

Need for distributed database systems, Need For Distributed Database System...

Need For Distributed Database Systems A distributed database is a set of database kept on multiple computers that appears to applications as a one database. As a result, an app

Define transitive dependencies, What do you understand by transitive depend...

What do you understand by transitive dependencies? Define with an example any two problems that can take place in the database if transitive dependencies are available in the datab

Whst is logical schema, Whst is logical schema ? Logical schema is the ...

Whst is logical schema ? Logical schema is the entire database.

Explain displaying an er schema as an er diagram, Explain the conventions f...

Explain the conventions for displaying an ER schema as an ER diagram? An E-R Diagram scheme might describe certain constraints to that the contents of a database must conform.

Extended star schema, Northwind Pty Ltd sells a variety of food products th...

Northwind Pty Ltd sells a variety of food products throughout the world.  They want to use the reporting features of SAP's Business Information Warehouse to better understand their

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