Using MIS (9th Edition)
Using MIS (9th Edition)
9th Edition
ISBN: 9780134106786
Author: David M. Kroenke, Randall J. Boyle
Publisher: PEARSON
Question
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Chapter 5, Problem 5.3UYK
Program Plan Intro

E-R model:

  • It is a tool for creating data model.
  • It is used for developers to describe the content of data model by using two functions called entities and relationships.

Entity:

  • It helps the user for tracking something in database.
  • Example entities in student database system are Student, Grade, Course, etc.

Relationships:

  • Entities have relationships among each other.
  • For example, in student database, a Student has a relationship to Major and Student has a relationship to Advisor.

Attribute:

  • It used to describe the entity characteristics.
  • Example attributes of student entity is Student_id, Student_name, Student_address, etc.

Identifier:

  • It is an attribute or group of attribute, but its value is related with one and only one entity instance.

Example of E-R diagram:

Using MIS (9th Edition), Chapter 5, Problem 5.3UYK

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