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Data flow diagrams

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Data flow diagrams

  1. 1. Data Flow Diagrams
  2. 2. What is a data flow diagram for?They look at data without considering the equipment needed.They are the first stage of designing a system.Show what data comes from and what data is needed
  3. 3. Source of dataThe OVAL = source of data (sink) This is a source of data e.g. order form from a customer Or an actual person…. The user, secretary, manager etcWe are not concerned with what happens to the data before itreaches a source, or what happens to it after it goes past it!
  4. 4. ProcessThe process BOX This is a process performed on the 1 data e.g. search, produce a graph, Search database perform calculation, create a mail merge letter, print Brief description of processEach process is numbered
  5. 5. Data StoreThe Open Rectangle This is where data is stored D1 Members file e.g. members file, letters file etc Each store is numbered Brief description of store
  6. 6. Direction of Data FlowArrows are used to show how symbols connect e ta bas a nto d np ut i ta ils i De Brief description of data used
  7. 7. Level 0 / Context diagramThis is an overview of the whole processOnly has one processDoes not show any data stores Book holiday Holiday Customer booking system Receipt
  8. 8. Task 1 – Create Level 0’s to show…How a secretary in a company produces a report.How a librarian produces a letter for overdue books.How a doctor produces a diet sheet for a patient.
  9. 9. Draw a Level 0 diagram for yoursystemMake sure that you draw the key.Make sure you label each item.
  10. 10. Level 1 diagramThis builds on the processes involved in here 1 Book holiday Holiday Customer booking system Receipt
  11. 11. Level 1 Diagram 1 Enquiry Customer details Availability D1 Customer recordsCustomer checked List of holidays 2 Payment made Holiday details Holiday D2 Bookings fileCustomer booked Receipt n rm atio Info k ing 3 Boo ConfirmationCustomer Printout of printed details