Division operation, Database Management System

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.

Posted Date: 3/6/2013 5:57:47 AM | Location : United States







Related Discussions:- Division operation, Assignment Help, Ask Question on Division operation, Get Answer, Expert's Help, Division operation Discussions

Write discussion on Division operation
Your posts are moderated
Related Questions
What Count function return in SQL? Count function within SQL returns the number of values. (Count function counts all the not null values in the exact column. If we need to cou

Explain ODBC? ODBC - Open DataBase Connectivity (ODBC) enable the integration of SQL along with a general-reasons programming language.

write on the various type of relationalkey

Single-Valued Dependencies A database is a collection of related information and it is therefore inevitable that some items of information in the database would depend on some

Which two tools are used to administer users for Active Directory?

Define raid? Briefly explain it? A range of disk organization methods, collectively called redundant arrays of independent disks (RAID) o   Improvement of reliability throug

What are the advantages of embedded query language? Give an example of an embedded SQL query. Embedded query language - SQL could be implemented within two ways. It can be us

What is a disjoint less constraint? Ans: It needs that an entity belongs to no much more than one level entity set.  Disjoint less constraint needs that an entity belongs to


Advantages And Drawbacks Of Ddbms  There are various reasons for building distributed database systems, with sharing of data, reliability and availability, and speedup of query