MGMT 430 Business Database Systems

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MGMT 430 Business Database Systems

• Sree Nilakanta
• Management Information Systems

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Data Modeling

• Primary Models
• Entity - Relationship
• Relational Model
• Object Model

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Entity - Relationship Model

• Focus on understanding corporate information
• Communication mechanism
• High level
• No implementation details

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E-R Model (contd.)

• Entity
• Something of importance to the user
• Object, thing, event
• Examples - Department, Employee, Sales

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E-R Model (contd.)

• Attribute
• Description of an Entity
• Principles of inclusion
• efficiency, non redundancy, simplicity
• Examples Employee (name, ssn, salary, etc.)

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E-R Model (contd.)

• Relationships
• Entities relate to other entities
• Common type - Binary
• Department relates to Employee

Departments
Employees
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E-R Model (contd.)

• Cardinality
• The maximum no. of instances allowed on each end
  of the relationship
• One-to-One
• One-to-Many
• Many-to-Many

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E-R Model (contd.)

• Example of a One-to-One

Faculty
1
has
1
Office
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E-R Model (contd.)

• Example of One-to-Many

Departments
1
has
N
Employees
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E-R Model (contd.)

• Example of Many-to-Many

Students
M
has
N
Courses
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Summary

• Entities are the major players in the drama
• Relationships define rules of the play