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

Define cascading rollback, Define Cascading rollback The phenomenon whe...

Define Cascading rollback The phenomenon where a single transaction failure leads to a series of transaction rollbacks is known as Cascading rollback.

What are the general transformation rules, What are the General Transformat...

What are the General Transformation Rules for Relational operations?  Ans: The transformation rules transform one relational algebra expression to AN EQUIVALENT ONE  1. E

Which is another name for weak entity, Which is another name for weak entit...

Which is another name for weak entity? Child is another name of weak entity.

Explain b-tree, What is B-Tree? A B-tree eliminates the redundant stora...

What is B-Tree? A B-tree eliminates the redundant storage of search-key values .It permits search key values to appear only once.

Database life cycle, Enumerate or state the steps in creating a relevant da...

Enumerate or state the steps in creating a relevant database of a shop.

Which model is used to store data in tree structures, 1. Which model is use...

1. Which model is used to store data in tree structures Ans: Hierarchical model is used to store data in tree structures

Eer diagram, Design an EER schema for the following application and transla...

Design an EER schema for the following application and translate the EER schema into relational schemas (and constraints). It is possible that some requirements cannot be captured

MS Access 2010 - Form Updates Table, Hi there, Have an issue with my Databa...

Hi there, Have an issue with my Database. I have: TblOrderDetails and FmOrderDetails TblCircuit and FmCircuit Whenever I add data into the Form, it will update the table as expect

Implementation of integrity rules, Question 1 Describe the following- ...

Question 1 Describe the following- Clustering Indexing Question 2 Explain the following with suitable real time examples- Implementation of Integrity rules

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