A diagrammatic representation of the flow of data through a process/system or sub-system/ sub-process.

Shows what happens to the data as it goes through a process.

Symbols and Symbols and Notations:Notations:

DFD NotationDFD Notation

Data Flow

Data Description

Process

Source orDestination

Data Store

Case Scenario 1:

The University of Zukota, located in central Africa, offers training courses in computer application development. Here is a brief description of the admission process for these training courses:

• Applications for courses have to be sent to the University's training department. Applications should contain personnel details, training course(s) desired and (intended) donor name.

• The training department’s staff stores the application details after some verification, and sends a letter of acceptance to the applicant and a letter of intimation to the respective donor.

• On receipt of the donor’s confirmation. A Visa letter is then issued to the applications.

Context Context DiagramDiagram

Training Databases

Applicant and Training Data

Donor Confirmation

Acceptance and VISA

Letter ofIntimation

Applicationof Courses

AdmissionProcess

DonorApplicant

The drawing of DFD normally starts at the top level often called

Is a general overview of how the system interacts with the external entities

Case Scenario 2:

A fragrance shop is having their mid year sale. All red tagged items are 50% off and green tagged items are 75% off. Items should be validated to give proper discounts. After discount was given, amount to be paid will be calculated. Printed receipt will be given to the costumer. The security will then check if the costumer has the printed receipt check for the purchased items before releasing.

Costumer Validate items

for discounts

Prices database

Compute for the

purchased items

Print Receipt

Verify the

Receipt

Security

Data Data DictionaryDictionary is a central depository of all the elements

that are used in a system a place where you look up the meaning of a place where you find the details of an

element e.g. numeric characters in data items, where

the data item is used, its initial value, data types, etc.Data names The data of the data item

Data description A brief description of the data item

Aliases The data name referred by another name

Data type The data type of the data item

Length The size of the data item

Data Values Permissible values that can be stored

Used In Which process(es) uses it

Data names STOCK-NO

Data description A unique number that identify each stock item

Aliases ITEM-NUMBER

Data type Character

Length 5

Data Values 10000-99999

Used In Data-entry procedureCheck-stk-no procedureUpdate-master procedure