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: ΠL(E1 ∪ E2) = (ΠL(E1)) ∪ (ΠL(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

Data, Explain three main attributes of data.

Explain three main attributes of data.

What are the disadvantages of relational approach, What are the disadvantag...

What are the disadvantages of relational approach? Disadvantages of relational approach: • Substantial hardware and system software overhead • May not fit all business models •

When is a transaction rolled back, When is a transaction rolled back? A...

When is a transaction rolled back? Any changes that the aborted transaction made to the database must be uncompleted. While the changes caused by an aborted transaction have be

What is the archtetype pattern, What is the archtetype/instance pattern? ...

What is the archtetype/instance pattern? The archetype/instance pattern happens when one entity tracks occurrences of another entity. A common example is the relationship among

What you understand by client-server environment, Problem: a) Briefly d...

Problem: a) Briefly describe what you understand by Client-Server environment b) The File Server is a simple form of Client-Server. Describe the principles of the File Serve

Define check point and its impact on data base recovery, Define check point...

Define check point and its impact on data base recovery.                  Ans:  There could be hundreds of transactions handled per minute, in a large on-line database system.

Explain key benefits of a content management system, Question: (a) What...

Question: (a) What do you meant by content management and briefly describe four major components of a Content Management System? (b) Explain key benefits of a Content Manage

single products ordered, For Colorado customers calculate the number of si...

For Colorado customers calculate the number of single products ordered. If a product is purchased on multiple orders, it should be counted only single time. The result should conta

Query optimization, what is meant semantic query optimization? how does it ...

what is meant semantic query optimization? how does it differ from other query optimization techniques?

Write short notes on data ware housing, Write short notes on data ware hous...

Write short notes on data ware housing? Data ware housing applications needs the transformation of data from many sources into a cohesive reliable step set of data configured a

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