When creating ERDs, which would most likely NOT be a source for entities?

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BlackTom AI · Accepted Answer

When constructing an ERD, understanding potential sources for identifying entities is key.

Option 1: Cost/benefit reports. These are financial and economic assessments that summarize cost and benefit analyses; they are not typical sources used to identify the real-world entities (things of interest) in a database, so this option is unlikely to be a primary source for entities.

Option 2: Data flows. Data flow diagrams (DFDs) depict movement of data between processes, stores, and external agents; while they show how data moves, they can also reveal the important data stores and the objects within them, which can lead to entity identification. This makes data flows a plausible source for entities.

Option 3: Use cases. Use cases describe interactions between actors and the system to achieve goals, often highlighting the major concepts and objects involved in system behavior, which can suggest candidate entities. Therefore, use cases are a reasonable source for identifying entities.

Option 4: External entities. In ER modeling, external entities (often represented as entities or as relationships to external sources) are commonly used to capture outside actors or systems that interact with the system, making them a natural source for entities or at least for identifying entities’ boundaries. This is a valid source.

Option 5: Level 0 DFD diagrams. Level 0 DFDs show high-level processes and data stores and can reveal the main data stores and data elements that map to potential entities; thus, they can guide entity identification. This is also a plausible source.

By comparing the options, it becomes clear that most of the listed items (data flows, use cases, external entities, Level 0 DFD diagrams) can contribute to identifying entities in an ERD. In contrast, cost/benefit reports are not about the structural elements of the data model and do not typically yield candidate entities. The reasoning above explains why cost/benefit reports are unlikely to be a primary source for entities in ERD design, while the others provide actionable insights for entity identification.

45582/46551: IST/BSAN 325 Systems Analysis and Design LEC Chapter 5 Review

When creating ERDs, which would most likely NOT be a source for entities?

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