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Data Flow Diagrams

Data Flow Diagrams. What the ***** 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. Source of data. The OVAL = source of data (sink).

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Data Flow Diagrams

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  1. Data Flow Diagrams

  2. What the ***** 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. 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 etc We are not concerned with what happens to the data before it reaches a source, or what happens to it after it goes past it!

  4. 1 Search database Process • The process BOX This is a process performed on the data e.g. search, produce a graph, perform calculation, create a mail merge letter, print Brief description of process Each process is numbered

  5. Data Store • The Open Rectangle This is where data is stored e.g. members file, letters file etc D1 Members file Each store is numbered Brief description of store Can be on a computer or in a physical location

  6. Direction of Data Flow • Arrows are used to show how symbols connect Details input into database Brief description of data used

  7. Some symbols are in Autoshapes Spend a little time creating the shapes and save them so that you can reuse them.

  8. Book holiday Holiday booking system Receipt Level 0 / Context diagram • This is an overview of the whole process • Only has one process • Does not show any datastores Customer

  9. 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.

  10. Draw a Level 0 diagram for your system • Make sure that you draw the key. • Make sure you label each item.

  11. 1 Book holiday Holiday booking system Customer Receipt Level 1 diagram • This builds on the processes involved in here

  12. Level 1 Diagram 1 Enquiry Customer details Customer records Availability checked D1 Customer List of holidays 2 Payment made Holiday details Bookings file Holiday booked D2 Customer Receipt Booking Information 3 Confirmation printed Customer Printout of details

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