ACG 4401

Data Model Examples:DFD’s and System Flowcharts

21

Context-Level Diagram

0

EmployeePayrollSystem

Employee Tax Form

Payroll Report

Time Sheet

Employee Payroll Check

Employee

Accounting Department

22

Level-0 DFD

1.0

CreateWeeklyPayrollRecord

Employee Data File

S1Employee Payroll Data File

S2

2.0

ComputeWeekly

Paycheck

3.0

PrepareWeeklyPayroll

Summary

4.0

PrepareEmployee

TaxForm

AccountingDepartment

Employee Record Paycheck Data

Payroll Record

Payroll Report

Employee Paycheck

Employee Tax Form

Time Sheet

Hours Worked

Employee Payroll Record

23

Level-1 DFD

1.0CreateWeeklyPayrollRecord

Employee Data FileS1

Employee Tax Form

Payroll Data FileS2

2.1Compute

GrossPay

2.3CreatePayrollCheck

2.2Compute

NetPay

3.2Print

WeeklyPayroll

Summary

3.1Sort

PayrollRecords byEmployee

4.2Print

EmployeeTax

Form

4.1Calculate

PayrollDeductions

Employee Paycheck

PayrollDeductions

Employee PayrollRecord

Time Sheet

Employee Record

Gross PayData

Net PayData

Hours WorkedPayroll Record

Sorted Records

Payroll Report

Employee

Accounting Department

24

Functional Primitive

4.1.2

CalculateNon-tax

Deductions

4.1.3

CalculateRetirementAllowance

4.1.4

CalculateEmployeeVacation

Pay

4.1.1

CalculatePayroll

TaxDeductions

4.2

PrintEmployeeTax Form

EmployeeData

EmployeeData

EmployeeData

Employee Tax Form

EmployeePayrollRecord

Employee Data

44

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.

45

User queries the computer. The computer accesses the table(s) in one of more data stores & presents a response to the user.

Update sequentialdata store from magnetic disk are input to the computer, along with the existing (old) master data – becoming the new master data

46

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.

47

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.

48

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

49

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