1. Data flow diagrams IPT 2010

2. data flow diagrams A data flow diagram provides more detail at a lower then a context diagram. Data flow diagrams represent the information system as a number of processes that together form the single process of a context diagram. DFD’s focus on the flow of data between information processes in a system.

3. Data flow diagrams They show where data is collected, organised, analysed, stored, processed, transmitted and displayed. DFD’s provide a simple technique for visualising the movement of data and describing what participants do, rather than what the computers do.

4. 4 symbols used in A DATA FLOW DIAGRAM Proce ss ExternalEntity Data Flow External Entity Data Store Data Store Process

5. Process: A circle is used to represent the processes or actions that transform inputs to outputs. Process

6. data flow Data Flow: An arrow is used to represent the flow of data between the process, external entity and data store.

7. External entity External Entity: A square or a rectangle represents any person or organisation that sends data to or receives data from the system. ExternalEntity

8. Data store Data Store: An open rectangle represents the location where data is stored. It could be a filing cabinet, hard disk or DVD. Data Store

9. example finding a book in a library Borrower Search Borrower Library Database Book Details Call Number Book Details Call Number

10. Example dOCTOR’S SYSTEM FOR INVOICING PATIENTS AFTER A VISIT Doctor’s record of visitPatientsMedicare Patient Fee Schedule Patient’s Records Medicare Records Medicare Records Accounts Receivable Calculat e Fee Prepar e Invoice Receive Paymen ts

11. ACTIVITY The marking system from the context diagram exercise is extended to include a spreadsheet to store and moderate the marks. Construct a data flow diagram to show the marking system.

12. textbook Read pg. 270 and pg.271 and answer ‘Group Task- Discussion’ Answer Question 14 on pg.273