Division operation, Database Management System

Assignment Help:

To do the division operation R1 ÷ R2, R2 should be a correct subset of R1. In the following example R1 have attributes A and B and R2 have only attribute B so R2 is a correct subset of R1. If we perform R1 ÷ R2 than the resultant relation will have those values of A from R1 that are related to all values of B present in R2.

Example

A

B

A1

B1

A1

B2

A2

B1

A3

B1

A4

B2

A5

B1

A3

B2

Let R1

If R2                    R3= R1 ÷ R2                      If R2                       R3= R1 ÷ R2

180_DIVISION operation.png

If R2                  R3= R1 ÷ R2                                               If R2             R3= R1 ÷ R2

1567_DIVISION operation1.png

Figure:  The Division Operation

Note:

               Degree of relation: Degree (R ÷ S)=Degree of R - Degree of S.


Related Discussions:- Division operation

What is a foreign key, What is a foreign key, and what is it used for? ...

What is a foreign key, and what is it used for? A foreign key is used to establish relationships between relations in the relational model. Technically, a foreign key is a colu

Explain the paths in the association network, Explain the paths in the asso...

Explain the paths in the association network We can analyze use of paths in the association network as given below: Calculate each operation Find associations whic

Generalization and specialization, design a generalization specialization h...

design a generalization specialization hierarchy for a motor vehicle sales company. the company sells motorcycles, passenger cars, vens and buses.

Example-revoke all on emp from mca12, Example:  //REVOKE ALL ON EMP FROM MC...

Example:  //REVOKE ALL ON EMP FROM MCA12;                              (All permissions will be cancelled) You can also cancel only some of the permissions. Drop: A user-

What is a view, What is a view? A view is a logical view on one or more...

What is a view? A view is a logical view on one or more tables.  A view on one or more tables i.e., the data from a view is not actually physically kept instead being derived f

Design and prototype, This assignment is worth 45% of your final grade for ...

This assignment is worth 45% of your final grade for this module.  Marks will be awarded as follows: Prototypes (wireframe and web based prototype) You are expected

Discuss how the bi-directional implementations are made, Discuss how the bi...

Discuss how the bi-directional Implementations are made. In bi-directional implementation of the association, a pair of references must implement every link. The declarations a

B+ tree, construct a B+ tree for the following set of key value (2,3,5,7,11...

construct a B+ tree for the following set of key value (2,3,5,7,11,19,23,29,31) in ascending order where the pointers that will fit in one node is as follows:A. four B. six C. eigh

Define deadlock term, a. Define the term "deadlock". There are four conditi...

a. Define the term "deadlock". There are four conditions that must hold before deadlock is possible. Name them. b. Outline an algorithm that detects whether there is a deadlock.

Cartesian product, If R1 and R2 are two relations or functions, then the re...

If R1 and R2 are two relations or functions, then the result of R3 = R1 × R2 is the combination of tuples that are in R1 and R2. The product is associative and commutative. Degr

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