2 Replies - 1456 Views - Last Post: 26 September 2012 - 05:54 AM Rate Topic: -----

#1 satislikev  Icon User is offline

  • New D.I.C Head

Reputation: 0
  • View blog
  • Posts: 12
  • Joined: 25-November 09

ER diagram question.

Posted 26 September 2012 - 05:38 AM

Hello !
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,

Attached File(s)



Is This A Good Question/Topic? 0
  • +

Replies To: ER diagram question.

#2 DarenR  Icon User is offline

  • D.I.C Lover

Reputation: 492
  • View blog
  • Posts: 3,271
  • Joined: 12-January 10

Re: ER diagram question.

Posted 26 September 2012 - 05:52 AM

give the actor an id and use that in cast.

like cast would have the cast_name and actor_id and what ever else you want
the actor would have actor_name, actor_id, and so on.
Was This Post Helpful? 0
  • +
  • -

#3 satislikev  Icon User is offline

  • New D.I.C Head

Reputation: 0
  • View blog
  • Posts: 12
  • Joined: 25-November 09

Re: ER diagram question.

Posted 26 September 2012 - 05:54 AM

View PostDarenR, on 26 September 2012 - 06:52 AM, said:

give the actor an id and use that in cast.

like cast would have the cast_name and actor_id and what ever else you want
the actor would have actor_name, actor_id, and so on.


I thought about that too. but if i use Actor ID , wouldn't the ID be count as a primary key?? (We may not use any primary key yet :(
Was This Post Helpful? 0
  • +
  • -

Page 1 of 1