Explain projection operation distribute over union operation, Database Management System

Assignment Help:

Illustrate the statement 'Projection operation distributes over the union operation'. Give an example.

Ans: Π_L(E₁ ∪ E₂) = (Π_L(E₁)) ∪ (Π_L(E₂))

This says that result acquired by projecting on an attribute set A, after taking union of two relations is similar as union of two relations each of which is a projection of original relations on A.

Related Discussions:- Explain projection operation distribute over union operation

Prepare a gantt chart for the stock control project, Prepare a gantt chart ...

Prepare a gantt chart for the stock control project: Scenario Lucas-TVS is the Leader in Auto Electricals in India today with 50 years experience in desig

Update city of first bank corporation to new delhi, Change the city of Firs...

Change the city of First Bank Corporation to ‘New Delhi' UPDATE COMPANY SET CITY = ‘New Delhi' WHERE COMPANY_NAME = ‘First Bank Corporation';

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

What is object identity, What is object identity? An object retains its...

What is object identity? An object retains its identity even if some or all the values of variables or explanations of methods change overtime.

Define the term- making common behaviour abstract, Making Common Behaviour ...

Making Common Behaviour Abstract Let us define abstraction "Abstraction means to focus on the necessary, inherent aspects of an entity and ignoring its accidental features". O

State about the use case diagram, State about the Use Case Diagram A u...

State about the Use Case Diagram A use case diagram represents a set of use cases, actors and their relationships. These diagrams shall be used to model context or requirement

E-R, Mention various steps required to draw an E-R Diagram. Draw an E-R Dia...

Mention various steps required to draw an E-R Diagram. Draw an E-R Diagram for Student Information System. Mention all suitable assumptions to justify your answer.

Can you scan double-sided documents and remove blank pages, Can you scan do...

Can you scan double-sided documents - and remove blank pages? Our software and imaging systems supports duplex scanning, at the same time scanning both sides of a page. Program

Create the database in oracle using ddl, The Assessment page has a link to ...

The Assessment page has a link to download a conceptual model, and a list of data. You are to map this conceptual model, and create the database in Oracle using your own DDL. T

Er schema can be represented by relation schemas , Q. Describe how an ER sc...

Q. Describe how an ER schema can be represented by relation schemas and constraints arising from ER design can be mapped to constraints on a relation schema. The entity rela

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages