SnarkDreams Database Data Models
ER Model
UML Model
Semantic Object Model
Questions, Answers, and Clarifications
- In CUSTOMER, CostsSubtotal (which somehow ended up named TotalCost in the Semantic Object model) is simply KagiPercent + Cost. You could leave this out of the database and instead derive it with a function when the value is needed. If you choose to do this, just add a note to your data structure diagram that you did so. Except for this one exception, I want all other attributes shown recorded in the database.
- Conceptually, US Customer is a subclass of Customer. However, when implementing it, it is probably simpler to include the State attribute in Customer. Just be sure to allow nulls in State when you do this. See the Semantic Object model for an example of what I'm talking about.
- In PRODUCT, name is the short name after the @ in the SD Needs document. Since these are unique, these names will serve as the product IDs. The description is the complete name in "quotes."
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