Multivalued attributes, Database Management System

Assignment Help:

For every multivalued attribute 'A', we make a new relation R that contains an attribute corresponding to plus the primary key attribute k of the relation that shows the entity type or relationship type that has as an attribute. The primary key of R is then mixture of A and k.

For instance, if a STUDENT entity has RollNo, Name and PhoneNumber where phone number is a multi-valued attribute then we will make a table PHONE (RollNo, Phone-No) where primary key is the combination. Please also reminder that then in the STUDENT table we need not have phoneNumber, instead it can be easily (Roll No, Name) only.


Related Discussions:- Multivalued attributes

Special comparison operator used in where clause-dml, Special comparison op...

Special comparison operator used in where Clause a.   between. ...and...It gives range among two values (inclusive) Example: SELECT ENAME, SAL FROM EMP WHERE SAL BETWE

Creating views with check option-data control, Creating views with check op...

Creating views with check option : This option limits those updates of data values that cause records to go off the view. The following instance tells this in more detail: Examp

Hashed file organisation, Hashed File Organisation Hashing is the most ...

Hashed File Organisation Hashing is the most common form of purely random access to a database or file. It is also used to access columns that do not have an index as an optimi

ER DIAGRAM, draw ER diagram of student entity and course entity where attri...

draw ER diagram of student entity and course entity where attribute of student entity are student roll, student name, student phone and student address and attribute of course enti

Define the term domain, Define the term Domain. For each n every attrib...

Define the term Domain. For each n every attribute there is a set of permitted values known as the domain of that attribute.

What is distributed system, What is Distributed system ? Distributed S...

What is Distributed system ? Distributed System - A distributed system consists of a number of processing parts in which are interconnected through a computer network and in

What is a virtual table that draws its data from the result, What is a virt...

What is a virtual table that draws its data from the result of an SQL SELECT statement? View is a virtual table that draws its data from the result of an SQL SELECT statement.

Define partial, Partial Key : It is a group of attributes that can uniquel...

Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.  Altern

Managing databases, 10A.53 Code an Oracle Database trigger to enforce the...

10A.53 Code an Oracle Database trigger to enforce the constraint that an employee can never change his or her department. 10A.54 Code an Oracle Database trigger to allow the

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