A process moves data from place to place in the system. On a data flow diagram, processes may move data between certain symbols (data stores, external entities and other processes). However, data may not be moved without a process. To help you understand appreciate this, fill in the cells of the following table. The cell entries should either be a) This cannot be done, e.g. data may not move from an external entity to another external entity (can it?), or b) an example of how data could be moved. An entry is provided below.
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Data moving FROM |
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| External entity | Process | Data store | ||
| Data moved TO: | External entity | N/A | ||
| Process | Customer information | |||
| Data store
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In this example, customer information may be moved from an external entity to a process (e.g. a customer gives their address and credit card information to a sales agent).
The "N/A" suggests data cannot be moved from a data store directly to an external entity, which is true (you need a process in between them).