Entity relationship modeling: Lesson 6

Question 1

What are the two conditions for a weak entity?

Answer 1

1. the entity is existence dependent

2. has a strong(identifying) relationship

Question 2

what is optional participation?

Answer 2

One entity occurrence does not require a corresponding entity occurrence in a particular relationship

Question 3

What is mandatory participation?

Answer 3

One entity occurrence requires a corresponding entity occurrence in a particular relationship

Question 4

What is a relationship degree? List all 3 of them

Answer 4

Indicates the number of entities or participants associated with a relationship. Unary relationship, Binary relationship and Ternary relationship