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

Express types of information available in mysql, Express types of informati...

Express types of information available in MySQL? Information as regards the result of queries:  This includes number of records affected by any SELECT or UPDATE or DELETE st

Create a database, The database will enable college administrators the abil...

The database will enable college administrators the ability to track students initial major. This will help college officials decide how best to prepare students for their goals an

Database models, why are older data models are being replaced by new data m...

why are older data models are being replaced by new data models

Can you delete data element, Can we delete data element, which is being use...

Can we delete data element, which is being used by table fields. No we cant delete data element.

What are the several forms of identity, What are the several forms of ident...

What are the several forms of identity? a) Value b) Name c) Built-in

Explain the terms primary key, Explain the terms primary key, candidate key...

Explain the terms primary key, candidate key, alternate key and secondary key. In the given table identify every key? STUDENT(SID,Regno, Name, City) Primary Key: The prim

Partial relation emp-get the details people with min salary, Let consider t...

Let consider the given partial relation EMP. Let us make some sub-queries for them EMPNO ENAME JOB SAL DEPTNO 7566

Describe the association - design, Describe the Association: Design  ...

Describe the Association: Design  Before we describe association design let us define association "Association is set of links between two objects in the object model". It is

What is a heterogeneous distributed database, What is a heterogeneous distr...

What is a heterogeneous distributed database? In a heterogeneous distributed database, dissimilar sites may use different schemas, and dissimilar dbms s/w. The sites may not be

Designing the hierarchy of a ldb?, What sorts of tables one can se in desig...

What sorts of tables one can se in designing the hierarchy of a LDB? Tables, which are having Foreign Key relations.

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