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

Architectural standard, Architectural standard: Designation : Archit...

Architectural standard: Designation : Architect , Consultant Job Profile : As a part of Oracle Fusion Middleware at Satyam, I am involved with Presales, Delivery, A

Query to list the employee name have 10000 salary, Consider employee table ...

Consider employee table of (i) and list names of department(s) for which average salary for department is more than 10,000. (SELECT d_name FROM dept WHERE d_code IN (SELECT d_c

Conflicting operations in schedule, Conflicting Operations in Schedule: ...

Conflicting Operations in Schedule: The three simple ways of interleaved instruction implement of transactions T1 and T2. Please note that in the following tables the first col

Update anomaly-data redundancy, Update Anomaly : This anomaly is occurred d...

Update Anomaly : This anomaly is occurred due to data redundancy. Redundant information makes updates more complex since, for example, varying the name of the instructor of MCS-014

Draw an e-r diagram and convert it to a relational schema, In an organizati...

In an organization several projects are undertaken. Each project can employ one or more employees. Each employee can work on one or more projects. Each project is undertaken on the

Develop a web site to present decision tree structure, I am going to develo...

I am going to develop a web site to present decision tree structure. For this, I want a web application with AJAX technology to connect the database and prepare the decision tree's

E-r diagram, Let us now make the E-R diagram for the student database as pe...

Let us now make the E-R diagram for the student database as per the explanation given in the previous section. We can also states the overall logical structure of a database usi

Case snerio, each publisher has uniqe name a mial addrs are also kept on ea...

each publisher has uniqe name a mial addrs are also kept on each pubisher.a publisher publish one book.a book publish y one publisher.book identified by isbn.each book writn by one

Define upgrade and downgrade, Define upgrade and downgrade? It gives a ...

Define upgrade and downgrade? It gives a mechanism for conversion from shared lock to exclusive lock is called as upgrade. It gives a mechanism for conversion from exclusive

What subschema expresses, What subschema expresses ? A subschema expres...

What subschema expresses ? A subschema expresses the external view. (External schemas are called also called as subschemas)

Write Your Message!

Name

Email id

Message

Verfication Code

User Account

All Pages