Set difference, Database Management System

Assignment Help:

Set Difference

If R1 and R2 are two union compatible relations or relations then result of R3 =R1- R2 is the relation that have only those tuples that are in R1 but not in R2.

Incase, R3 will have tuples such that R3 = {t | R1 ∋ t ∧ t∉R2}.

 

Example:

 

R1

 

X

Y

A1

B1

A7

B7

A2

B2

A4

B4

 

 

 

  R2  

A

B

A1

B1

A2

B2

A3

B3

A4

B4

 

 

R1-R2 =

 

 

 

R1-R2 =

A

B

A3

B3

 

R2-R1=

 

 

 

R2-R1=

A

B

A7

B7

 

 

 

Note: -1) Difference operation is not commutative, i.e.,

 R1 - R2 ≠ R2 - R1

2) Difference operation is not associative, i. e.,

R1 - (R2 - R3) ≠ (R1 - R2) - R3


Related Discussions:- Set difference

Describe the concepts of structural semantic data model, Question 1 List a...

Question 1 List and explain various Normal Forms. How BCNF differs from the Third Normal Form and 4th Normal forms? Question 2 Describe the concepts of Structural Semantic Da

Visio diagram - database, The database depicted in the Visio diagram descri...

The database depicted in the Visio diagram describes Proceeding , Article , Researcher , article PublishedIn a proceeding, article WrittenBy researchers and proceedings Edi

What is completeness constraint on generalization, What is completeness con...

What is completeness constraint on generalization? Define the variation between total and partial design constraint. Give an example each.       Ans: Completeness Constraints

Database tables design and test queries, Load sample data into the database...

Load sample data into the database tables design and test queries to return the following information • All rows and columns for employees • All rows and columns for customers •

Define serializable schedule, Define Serializable schedule Serializable...

Define Serializable schedule Serializable schedule: An interleaved schedule of much more than one transaction is known as a serializable schedule, if it is equal to some serial

Explain algorithm of er to relational mapping, Explain algorithm of ER To R...

Explain algorithm of ER To Relational Mapping ? ER-to-Relational Mapping Algorithm: 1) Step 1: Mapping of regular entity types: For each strong entity type E, form a relatio

How can you terminate the mysql server, How can you terminate the MySQL Ser...

How can you terminate the MySQL Server? Typing the following in Command prompt will shut down the server completely as root user % mysqladmin -u root -p shutdown

Why were functional methods fashionable in early days, Why were functional ...

Why were functional methods fashionable in early days? These are inspired directly by computer architecture and thus popular among computer scientist in early days. The divisio

What is an e-r model and draw an e-r diagram for the company, What is an E-...

What is an E-R model? Draw an E-R Diagram for the company database with following Descriptions? The company is organized within departments. Each department has a unique name a

Assign, #quesDefine a job scheduling strategy that will meet business requi...

#quesDefine a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pi

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