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. Maximum cardinality: It is referred as maximum number of entities that are involved in a relationship. Examples of maximum cardinality: The three examples of maximum cardinality are: l:N(one to Many relationship) 1:1(one to one relationship) N:M.(Many to many relationship) Minimum cardinality: It gives the minimum number of entities that are required for relationship. Controls on minimum requirements are referred as minimum cardinality. Examples of minimum cardinality: The two examples of minimum cardinality are: It could contain 0 relationship It could contain 1 relationship

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Chapter 5, Problem 5.5CE5

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.

Maximum cardinality:

It is referred as maximum number of entities that are involved in a relationship.

Examples of maximum cardinality:

The three examples of maximum cardinality are:

l:N(one to Many relationship)

1:1(one to one relationship)

N:M.(Many to many relationship)

Minimum cardinality:

It gives the minimum number of entities that are required for relationship.

Controls on minimum requirements are referred as minimum cardinality.

Examples of minimum cardinality:

The two examples of minimum cardinality are:

It could contain 0 relationship

It could contain 1 relationship

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