Key constraint - relational constraints, Database Management System

Assignment Help:

This constraint shows that the key attribute value in each tuple must be unique, i.e., no two tuples have the similar value for the key attribute. This is because the value of the primary key is used to recognize the tuples in the relation.

 

Example: If A is the key attribute in the following relation R than A1, A2 and A3 must be unique.

 

A

 

B

 

A1

 

B1

 

A3

 

B2

 

A2

 

B2

 

Example: In relation PERSON, PERSON_ID is primary key so PERSON_ID cannot be given as the similar for two persons.

Integrity Constraint

There are two kinds of integrity constraints:

  • Entity Integrity Constraint
  • Referential Integrity Constraint

Related Discussions:- Key constraint - relational constraints

Normalization, in case of functional dependencies how we get the higher nor...

in case of functional dependencies how we get the higher normal form.

Introduction to Database Design and Development, Every School has many teac...

Every School has many teachers and many students. Each student is assigned to one school and each teacher works for one school only. Each teacher teaches more than one subject but

How to rearrange the execution order for efficiency, Rearrange the Executio...

Rearrange the Execution Order for Efficiency  Rearranging execution order for efficiency means executing such job that requires less execution time. By rearranging the object

Design an entity relation model, Funky Festivals Specification Funky Fe...

Funky Festivals Specification Funky Festivals organise music festivals which take place at various venues throughout the UK.  A venue needs to be booked before a Festival can t

Provide the steps involved in ethical analysis, Question : Mr. Smith Ha...

Question : Mr. Smith Harry has a car manufacturing company which has recently integrated management information system. He wishes to obtain more information on ethics and socia

Differentiate between natural join and outer join, Differentiate between na...

Differentiate between natural join and outer join? Natural join is a binary operator which is written as (R * S) where as R and S are relations. The output of the natural join

Describe dynamic model, Describe Dynamic Model. The dynamic model speci...

Describe Dynamic Model. The dynamic model specifies allowable sequences of changes to the objects from an object model. It contains event trace diagrams describing scenarios. A

What is meant by functional dependencies, What is meant by functional depen...

What is meant by functional dependencies? Consider a relation schema R and α C R and β C R. The functional dependency α ->β  holds on relational schema R if in any legal relati

Give short note on the following terms- dirty pages and etl, Give short not...

Give short note on the following terms:Dirty pages and ETL a.) Dirty pages. These are buffer pages which comprise modifications which haven't been written to disk. b.

Database schemas and dependencies, 1. Staff(staffID, firstName, lastName, a...

1. Staff(staffID, firstName, lastName, availabilityID, experience, phone, mobile, email); 2. Availability(availabilityID, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday,

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