Many-to-many relationship, Database Management System

For each m:n relationship type R, we make a new table (say S) to represent R. We also contain the primary key attributes of both the participating entity types as a foreign key attribute in S. Any easy attributes of the m:n relationship type (or easy components of a composite attribute) is also contain as attributes of S.

For example, the m: n relationship taught-by among entities COURSE and FACULTY should be shown as a new table.  The structure of the table will contain primary key of COURSE and primary key of FACULTY entities

A new table TAUGHT-BY will be created as: Primary key of TAUGHT-By table

 

ID

 

Course_ID

 

{Primary key of FACULTY table}

 

{Primary key of COURSE table}

 

 

Please note that since there are no attributes to this relationship, thus no other fields.

Posted Date: 3/6/2013 6:27:46 AM | Location : United States







Related Discussions:- Many-to-many relationship, Assignment Help, Ask Question on Many-to-many relationship, Get Answer, Expert's Help, Many-to-many relationship Discussions

Write discussion on Many-to-many relationship
Your posts are moderated
Related Questions
Java program for horrizontal fragmentation in distributed database

State the process of Rearranging Classes and Operations The various, yet similar operation of different classes can be slightly modified thus that they can be covered by a sin

Discuss the problem of Spurious tuples and how we may prevent it.    Ans:  A spurious tuple is, mainly, a record in a database that gets created while two tables are joined bad

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

State the definition of association An association is a structural relationship which specifies that objects of one thing are connected with objects of another. In UML, asso

Explain Candidate Key and Super Key A super key is a set of one or more than attributes that, taken collectively, permits us to identify uniquely a tuple in the relation. Wher

what problems are raised by the database? why is it so controversial? why is data quality an issue?

Example : Search the name, department number and salary of employees drawing minimum salary in that department. SELECT ENAME, SAL, DEPTNO  FROM EMP WHERE SAL IN (SELECT MI

Which operation is used if we are interested in only certain columns of a table? PROJECTION operation is used if we are interested in only certain columns of a table.

Describe Specialsation and generalization? Specialisation /generalization: This is a top down and bottom up approach to the design of database. It displays the IS_A relation