In ER digram we have an assignment and our teacher forces us to use at least an IS-A relation, i Just wonder if it is possible for an entity to have is-a relationship with another entity but do not have any attribute ? For example:
An actor ISA cast.
Cast have a name.
all i need from the actor is to have a name, no date of birth, telephone number or etc.
I also attached my diagram can someone say if it have any problem or not.
P.S. we MUST use at least one ISA relation we may not use primary key,
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