Multivalued attributes, Database Management System

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.

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