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databaseentity-relationshiprdbms

ISA relationship ER diagram

I want to add different type of departments to an entity called department in a ER diagram.Can I use ISA relationship for it.there are more than 2 departments.does ISA relationship can have more than 2 subclasses?

Solution

  • A supertype can have any number of subtypes. However, it's only useful to define subtypes if they'll have their own attributes or relationships. If not, a type attribute is sufficient.