Example Data Flow Diagram - brianhigh/data-workshop GitHub Wiki

• Context Diagram with Gane/Sarson Symbols
• Context Diagram with Yourdon/DeMarco Symbols and Curved Lines
• Context Diagram with Yourdon/DeMarco Symbols and Curved Lines without Subject Entity

• Level 1 Data Flow Diagram (v1) with Angled Lines
• Level 1 Data Flow Diagram (v1) with Curved Lines
• Level 1 Data Flow Diagram without Subject Entity

You would normally also include Level 2, Level 3, etc., as needed, to clarify the system design to the point where there would be no further ambiguity as to how it should be implemented by a developer.

While a few different styles (symbols, lines) of the diagrams are listed here, you would want to pick the best style for your purposes and stick to that for the entire set of DFDs. Also, you would want to be consistent in your scope — that is, which entities you will be modeling — from the context diagram (level 0), down through all of the lower levels. Keep the inclusion and naming of various data flows consistent as possible. At the more detailed lower levels, you may break out the generic data flows into more specific ones, relating more closely to actual data sources or data stores (such as individual data files) which may already be known and rather fixed at this point in your research. Try not to do any database design at this point though.