Question

I need to draw an ERD and Standard Notation Format based on info given. My problem is that I don't know how to show a double Primary key as a Foreign key in my ERD and in SNF. My Customer table needs to reference my Phone table which is as follows: PHONE(Manf_no(PK), Model_no(PK)).

Answer 1

Since each customer can have more than one phone I presume I need to create a new entity? The problem is that this new entity will need a triple PK? Can that be done and how?