The document describes different levels of data flow diagrams (DFDs) used to illustrate the flow of data in a system. It explains that a context-level DFD is the most basic, showing one main process and external entities. Level 1 DFDs break the main process into sub-processes and identify data stores. Level 2 DFDs provide more detail about the sub-processes such as inputs, outputs, and data flows. Examples of each level are provided for a hardware shop management system to demonstrate how the diagrams become more detailed at each level.

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3. Data Flow Diagram
A data flow diagram (DFD)
illustrates how data is
processed by a system in
terms of inputs and outputs.
As its name indicates its focus
is on the flow of information,
where data comes from,
where it goes and how it gets
stored.
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4. Types of Data Flow Diagram
• Context Level
• Level 0
• Level 1
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5. Context Level
• It is the most basic form of DFD.
• It aims to show how the entire system works at a
glance.
• There is only one process in the system and all the
data flows either into or out of this process.
• It demonstrates the interactions between the
process and external entities.
• It doesn’t contain Data Stores.
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6. External Entities :
Context Level
Cashier Customer
Dealer Owner
Manager
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7. Context Level
0
Hardware Shop
Management System
Main Process :
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8. Context Level
0
Hardware Shop
Management System
Cashier
Collect Cash
Receipt
Report
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9. Context Level
0
Hardware Shop
Management System
Owner
Account Details
Feedback
User info
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10. Context Level
0
Hardware Shop
Management System Manager
Feedback
Employee Details
Transaction Details
Inventory Details
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11. Context Level
0
Hardware Shop
Management System
Customer
Offer
Pay cash
Receipt
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12. Context Level
0
Hardware Shop
Management System
Customer
Payment Details
Order Details
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13. Level 1
• Its aim to give an overview of the full system.
• It look at the system in more detail.
• Major processes are broken down into sub-
processes.
• Level 1 DFD’s also identifies data stores that are used
by the major processes.
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14. Level 1
1.0
Administration
2.0
Inventory
Management
3.0
Sales
Management
4.0
Payroll
5.0
Supply Process
Sub processes:
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15. Administration
1.0
Level 1
Employee info
Feedback
Owner
D2 Employee
Check, Update, Add info
Authentication
D3 Customer
Feedback
Check info
D4
Give Bills
Info
Check
Transaction
Bills
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16. Inventory
Management
2.0
Level 1
Add New Items
Feedback ManagerD1
Record
Save
Item Data
Update Price
Product
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17. Sales
Management
3.0
Level 1
Receipt
Collect
Cashier
Customer
Offer
Pay Cash
D3 Customer
Report
Save info
D4
Transaction
info
Save
Transaction
Bills Bill Details
Manager
Check Transaction
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18. Payroll
4.0
Level 1
Time Worked
Pay
Cashier
Owner
Give wage
D2 Employee
Give
Employee
Info
Feedback
Pay
Dealer
Pay
Manager
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19. Supply
Process
5.0
Level 1
Give Order Report
Check Inventory
Status
Manager
Feedback
Order Report
Dealer
Supply
Produce
D1 Product
Save New
Product
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Level 1
Administration
1.0
Inventory
Management
2.0
Sales
Management
Payroll
Supply Process
4.0
3.0
5.0
Inventory Details
Sales Details
Give Supply Cost
Inventory
Details

21. Level 2
• DFD Level 2 then goes one step deeper into parts of
Level 1.
• It may require more text to reach the necessary level
of detail about the system’s functioning.
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22. Level 2
1.0 Administration Process
Owner D2 Employee
Save New Info
1.1
1.2
Create New Info
Change Info
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23. Level 2
1.0 Administration Process
Owner
Report
D4 Bills
Surety
1.3
Check Transaction
Give
Info
Check Bills
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24. Level 2
2.0 Inventory Management
Manager
D1 ProductSave New
Item
2.1
2.2
Add New Item
Add New Category
D5 Category
Save New
Category
Feedback
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25. Level 2
2.0 Inventory Management
Manager
New Price
D1 Product
Save New
Price
2.3
Change Item
Price FeedbackFeedback
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26. Level 2
3.0 Sales Management
Cashier
Customer
Check username,
password
3.1
3.2
Login System
Create Bill and
Receipt
Save
Report
Authenti-
cation
D3
D4 Bills
Customer
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27. Level 2
3.0 Sales Management
Cashier
Customer Details
D3 Customer
Save New
Customer
3.4
Add New
Customer
Feedback
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28. Level 2
3.0 Sales Management
Manager
Request
D4 Bills
Request
3.5
Check Bills
Bill Details Details
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29. Calculate
Employee
Pay
4.1
Level 2
Give Wage
Employee info
Owner
D6 Salary
Save Info
Cashier
Time
Worked
No
of
Cashier
D2
Give Info
Feedback
Employee
4.0 Payroll
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30. Level 2
4.0 Payroll
Manager
Pay
D6 Salary
4.2
Employee
Pay
Cheque
Give
Salary
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31. Level 2
5.0 Supply Process
Manager
Dealer
5.1
5.2
Give List
Product
Ship Order
Invoice
Save New Item
Feedback
D1 Product
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32. Use Case Diagram

33. Use Case Diagram

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