Intersection, Database Management System

If R1 and R2 are two union compatible relations or functions, then the result of R3 = R1 ∩R2 is the relation that contains all tuples that are in both the relations In other words, R3will have tuples such that R3 = {t | R1 ∋ t ∧ R2 ∋ t}.

Example:

 

 R1

A

B

A1

B1

A2

B2

A3

B3

A4

B4

  R2                     

A7

B7

X

Y

A1

B1

A7

B7

A2

B2

A4

B4

 

R3 = R1 ∩ R2 is

 

 

R3 = R1 ∩ R2 is

A

B

A1

B1

A2

B2

A4

B4

 

Note: 1) Intersection is an associative operation, i.e., R1 ∩ (R2 ∩ R3) = (R1 ∩ R2) ∩ R3

2) Intersection is a commutative operation, i.e., R1 ∩ R2 = R2 ∩ R1

Posted Date: 3/6/2013 5:45:16 AM | Location : United States







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

Write discussion on Intersection
Your posts are moderated
Related Questions
Discuss the mechanism to read data from and write to a disk? Disk read/write heads are mechanisms in which read data from or write data to disk drives. The heads have gone by

Derived horizontal fragmentation: Some applications may include a join of two or more relations. If the relations are stored at dissimilar locations, there may be a major overhead


Write an sql statement to find what is the percentage of home policies which are from the state of Arizona out of all Home policies by Policy Value.

What are stored-procedures? And what are the advantages of using them? Stored procedures are database objects that perform a user defined operation. A stored procedure can have


Question 1 Explain the 10 reasons to use MySQL Question 2 Write the SQL statements to demonstrate the following using SELECT command Expression Evaluation ORDER BY

Define a table in SQL known as Client that is used to store information about the clients. Define CLIENT_NO as the primary key whose first letter must begin with ‘C'. Also ensure t

MySQL Database Merge Project Description: I have two databases, I need merge the data of one database into another Work to be done online right now. Payment can be done

One-to-many : An entity in A is related with any number of entities in B. An entity in B is related with at the most one entity in A. Example: Relationship between faculty and d