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:

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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:

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