I'm studying for a database class and came across this EERD:

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Very simple EERD however, I'm wondering- how can I go about and convert this to a simple ERD instead? From my understanding, the only thing different about an EER is that it shows the specialization, generalization, partitioning, and aggregation - for this above diagram: specialization of course.

So if I were to remove the specialization entities for VEHICLE (Motorcycle, Car, SUV, Truck), would this diagram then be considered an ERD? That wouldn't make sense though, wouldn't it be important to show those relationships on an ER diagram?

If someone can tell me how I would go about converting this to an ER diagram, that would really help.

1 Answer 1


The only way I know of is one I can't recommend.

If you convert your EERD into a relational design (with tables, etc.) using some technique like "class table inheritance", you have now disguised the fact that the original EERD contained a generalization/specialization pattern.

If you now turn around and reverse engineer that back to an ERD, you have something that satisfies the requirements of your question. But that's grotesque. It conceals the original intent rather than revealing it. Why would anyone ever want to do that?

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