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

Data model, data models are being replaced over years. Reasons and why does...

data models are being replaced over years. Reasons and why does that happen?

Differentiate between b-tree and b+ tree, Differentiate between B-tree and ...

Differentiate between B-tree and B + tree    Ans:  A B-tree (or Balanced Tree) is a search tree along with additional constraints that makes sure that the tree is all the time

What is the concept of knowledge discovery in database, Data Warehousing & ...

Data Warehousing & Mining 1. What is the concept of knowledge discovery in database? 2. Describe the following types of Multidimensional Data Models. • Stars, Snowflakes and

Key to represent relationship between tables is called, Key to represent re...

Key to represent relationship amongs tables is called ? A Key that represent the relationship between tables is called Foreign Key.

Er diatgrams, Ask q“A database will be made to store information about pati...

Ask q“A database will be made to store information about patients in a hospital. On arrival, each patient’s personal details (name, address, and telephone number) are recorded wher

RDBMS, what is RDBMS? how it works? good example.

what is RDBMS? how it works? good example.

Binary relationship, explain in details about one to one binary relationshi...

explain in details about one to one binary relationship

E r diagram, how to make an e r diagram?

how to make an e r diagram?

Define deadlock prevention, Define Deadlock prevention These protocols...

Define Deadlock prevention These protocols make sure that the system will never enter a deadlock state. There are two methods to deadlock prevention. One approach makes sure t

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