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

Search the name department number and salary of employees , Example : Searc...

Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO  FROM EMP WHERE SAL IN (SELECT MI

Which is a legal expression in sql, Which is a legal expression in SQL? ...

Which is a legal expression in SQL? SELECT NAME FROM EMPLOYEE is a legal expression in SQL.

What is a select operation, What is a SELECT operation? The select oper...

What is a SELECT operation? The select operation selects tuples that please a given predicate. We use the lowercase letter σ to denote selection.

Which types of data supported by mysql, Which types of data supported by My...

Which types of data supported by MySQL for Time and Date formats?  MySQL supports a number of time and date column formats: Some of them are 1) DATE 2) DATETIME 3) TIM

Explain the management of data store, Explain the Management of Data Store ...

Explain the Management of Data Store Every system irrespective of its nature of application requires storing permanent data for consequent use in problem solving. Some objects

Define null values, Define null values. In some cases a certain entity ...

Define null values. In some cases a certain entity may not have an applicable value for an attribute or if we do not know the value of an attribute for a certain entity. In the

Concatenation operator-data manipulation language, Concatenation operator ...

Concatenation operator Example : Printing name and job as one string as column name employees: SELECT ENAME||JOB "EMPLOYEES" FROM EMP;

What is serializability, What is serializability? Explain its types? Th...

What is serializability? Explain its types? The data base system must control concurrent implementation of transactions, to ensure that the data base state remains consistent.

Need for client server computing, Need for Client Server Computing- Client/...

Need for Client Server Computing- Client/Server (C/S) architecture includes running the application on multiple machines in which every machine with its component software tackles

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