1. Data Model Examples: DFD’s and System Flowcharts
ACG 4401
Data Model Examples:
DFD’s and System Flowcharts

2. Context-Level Diagram
Employee
Payroll
System
Employee Tax Form
Payroll Report
Time Sheet
Employee Payroll Check
Employee
Accounting Department 21

3. Employee Payroll Record
Level-0 DFD
1.0
Create
Weekly
Payroll
Record
Employee
Data File S1 S2
2.0
Compute
Paycheck
3.0
Prepare
Summary
4.0
Tax
Form
Accounting
Department
Employee Record
Paycheck Data
Payroll Record
Payroll Report
Employee Paycheck
Employee Tax Form
Time Sheet
Hours Worked
Employee Payroll Record 22

4. Level-1 DFD Employee Accounting Department 23 1.0 Create Weekly
Payroll
Record
Employee Data File S1
Employee Tax Form
Payroll Data File S2
2.1
Compute
Gross
Pay
2.3
Check
2.2
Net
3.2
Print
Summary
3.1
Sort
Records by
Employee
4.2
Tax
Form
4.1
Calculate
Deductions
Employee Paycheck
Employee Payroll
Time Sheet
Employee Record
Gross Pay
Data
Net Pay
Hours Worked
Payroll Record
Sorted Records
Payroll Report
Employee
Accounting Department 23

5. Functional Primitive 4.1.2 Calculate Non-tax Deductions 4.1.3
Retirement
Allowance
4.1.4
Employee
Vacation
Pay
4.1.1
Payroll
Tax
4.2
Print
Tax Form
Data
Employee Tax Form
Record
Employee Data 24

6. The data-entry clerk keys in an input document into the computer
The data-entry clerk keys in an input document into the computer. The computer accesses data in a data store 1 and in data store 2 to edit/validate the input. The computer displays the input, including any errors. The clerk compares the input document to the display, keys corrections as necessary, and accepts the input. The computer updates the table in data store 2 and notifies the clerk that the input has been recorded. 44

7. User queries the computer
User queries the computer. The computer accesses the table(s) in one of more data stores & presents a response to the user.
Update sequential data store from magnetic disk are input to the computer, along with the existing (old) master data – becoming the new master data 45

8. The user batches the input documents, prepares batch totals, and keys the documents into the computer. The computer records the inputs on disk and notifies the user as each input is accepted. The user files the input documents in numerical sequence. At the end of the batch, the computer prepares an exception & summary report that includes batch totals. The user compares the computer batch totals to those prepared earlier. 46

9. A data entry clerk enters documents into a networked PC system
A data entry clerk enters documents into a networked PC system. The system records the inputs on a disk and notifies the user of the acceptance of each input. The documents are then forwarded to a different clerk who keys the documents again. Differences are resolved and the event data are updated to reflect the verifications and corrections. 47

10. A clerk scans a document into the computer
A clerk scans a document into the computer. Use the data from the scanned document, the computer updates the data store(s) 48

11. A clerk scans a document into the computer
A clerk scans a document into the computer. The computer routes an image of the scanned input to a data entry clerk, who keys data from the documents image into the computer. The computer records the data with the scanned document 49