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

To eliminate duplicate rows-data manipulation language, To eliminate duplic...

To eliminate duplicate rows (distinct operator)  Example: SELECT DISTINCT DEPTNO FROM EMP;

Draw an e_r model in oracle, Draw an E_R Model for the following: An or...

Draw an E_R Model for the following: An organization uses number of items of a equipment to generates goods. Each item is at one LOCATION, of one TYPE and has a DETAILED_DISCRI

Relational database management, For this application, we will consider IBM ...

For this application, we will consider IBM DB2 catalog data (i.e., metadata) for IBM's enterprise-class servers running the z/OS (formerly OS/390 or MVS) operating system.  One of

Explain the need for the bcnf normal form, Surgeons identified by doctor ID...

Surgeons identified by doctor ID (DOCID) operate on patients identified by patient ID (PATID) in operating theaters identified by room numbers (ROOMNO). Each surgeon can operate on

Write query to insert data in student table, Consider student (std_id, std_...

Consider student (std_id, std_name, date_of_birth, phone, dept_name). Put the data for a student with student id200, name arun, birth date 1 February, 1985, phone number (01110 328

Mysql database merge, MySQL Database Merge Project Description: I hav...

MySQL Database Merge Project Description: I have two databases, I need merge the data of one database into another Work to be done online right now. Payment can be done

What is a recursive relationship, Question: (a) Can a set of data requi...

Question: (a) Can a set of data requirements be correctly modelled by two or more different ER diagrams? Explain your answer. You may use a small example, if you think it will

Illustrate the term- abstracting out common behaviour, Illustrate the term-...

Illustrate the term- Abstracting Out Common Behaviour Inheritance is not every time recognised during analysis phase of development, thus it is necessary to re-evaluate object

Explain the use of constraints in functional model, Explain the use of cons...

Explain the use of constraints in functional model with suitable example. A constraint shows relationship between two objects at same time, or   among various values of the sam

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