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

Illustrate the cardinality of relationship, Cardinality of Relationship ...

Cardinality of Relationship One-to-One Only one entity of the first set is linked to only one entity of the second set. E.g. A teacher teaches a student. Only one teacher

Need database normalization and database analysis, Developer is required to...

Developer is required to do a task including: - Database Normalization - Database Analysis - ERM Diagram Details can be provided and then you can change your bid accord

Explain trigger, Explain trigger? Trigger: A database trigger is proc...

Explain trigger? Trigger: A database trigger is procedural code which is automatically executed within response to certain events on a particular table in a database. Trigger

Main difference between read-only and update methods, What is the main diff...

What is the main difference between read-only and update methods? A read-only method does not affect the values of a variable in an object, whereas an update method may alter t

A Biological Database on Viruses, How to create a biological database based...

How to create a biological database based on viruses. How to decide which attribute should be there in the table and schema? How to identify the primary keys, foreign keys, domain,

Emergence of client server architecture, Emergence of Client Server Archite...

Emergence of Client Server Architecture Some of the pioneering work that was completed by some of the relational database vendors permitted the computing to be distributed on m

What is deadlock, What is deadlock? Neither of the transaction can ever...

What is deadlock? Neither of the transaction can ever proceed with its normal implementation. This situation is known as deadlock.

Tour Operator Agency Database , #A multinational tour operator agency has g...

#A multinational tour operator agency has gained new business growth in the North American market through the use of social media. Its operation has expanded by 50% within six mont

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