Tutorial 10 Physical DFD and Physical ERD

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Tutorial 10 Physical DFD and Physical ERD

• SEG3430 Systems Analysis and Design

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Outline

• Physical Data Flow Diagram
• Physical Entity Relationship Diagram

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Logical and Physical DFD

• DFD is categorized as
• Logical DFD
• Shows how business operates
• It is concerned with how the system will be
  constructed.
• Describes business events
• Physical DFD
• Shows how the system will be implemented
  including software, hardware, file, people etc.

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The Physical DFD

• Contains the same components as the logical DFD
• The same rules pertaining to balance and
  decomposition apply
• Contains additional details describing how the
  system will be built

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Steps to create the physical DFD

• 1. Add implementation references
• 2. Draw a human-machine boundary
• 3. Add system-related data stores, data flows and
  processes
• 4. Update data elements in the data flows
• 5. Update the metadata in the CASE repository

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Example 1 for physical DFD

• The CD Selections Process.

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Example 2 for physical DFD

• The Bank system.

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The Physical ERD

• Contains the same components as the logical ERD
• The same rules pertaining to cardinality and
  modality apply
• Contains additional details describing how the
  data will be stored, in a file or database table
• Additional metadata content required

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Steps to create physical ERD

• Change entities to tables or files
• Change attributes to fields
• Add primary keys
• Add foreign keys
• Add system-related components

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Example 3 for physical ER

• The Appointment system
• Six main categories
• Patient
• Appointment
• Doctor
• Bill
• Payment
• Insurance company

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Example 4 for physical ER

• The CD Selections
• six main categories
• Marketing Material
• CD
• Inventory
• Vendor
• Customer
• Hold

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