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

Relational operations, Let us now talk about the relational operations: ...

Let us now talk about the relational operations: SELECT The select operation is used to select few specific record from the database based on different criteria, This is a un

What is relational calculus, What is Relational calculus? Relational c...

What is Relational calculus? Relational calculus is a Non- Procedural language.

What count function return in sql, What Count function return in SQL? C...

What Count function return in SQL? Count function within SQL returns the number of values. (Count function counts all the not null values in the exact column. If we need to cou

Physical location of record is determined by which formula, The physical lo...

The physical location of a record is determined by which mathematical formula that transforms a file key into a record location? The physical location of a record is determined

Explain strict two-phase locking, Explain Strict Two-Phase locking A tr...

Explain Strict Two-Phase locking A transaction T does not release any type of its exclusive (X) locks until that transaction commits or aborts. In this method no other transact

Skills required, wrie a report on whether a BSc n information systems devel...

wrie a report on whether a BSc n information systems develops the skills required by employers in Database administration

Misuse of data or a database, As with other software, databases can potenti...

As with other software, databases can potentially be used for unethical purposes. As a database developer, and a consumer, you should recognize database misuse, and how it may affe

What is a b+-tree index, What is a B+-Tree index? A B+-Tree index takes...

What is a B+-Tree index? A B+-Tree index takes the form of a balanced tree in which each path from the root of the root of the root of the tree to a leaf of the tree is of the

What are the uses of odbc, What are the uses of ODBC? Under what circumstan...

What are the uses of ODBC? Under what circumstances we use this technology? ODBC expose database capabilities within a standardized way to the application programmer by an ap

Construct an er diagram for a hospital, Construct an ER diagram for a hospi...

Construct an ER diagram for a hospital along with a set of patients and a set of medical doctors Associate with every patient a log of the several tests and examinations conducted.

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