HARDEST ORDER EVER - QUESTIONS AND ANSWERS 5.4 Who is the...

QUESTIONS AND ANSWERS
5.4 Who is the author of the entity-relationship data model?
5.5 Define entity. Give an example of an entity (other than one presented in this chapter). 5.7 Define attribute. Give an example attribute for the entity in your answer to Review
Question 5.5.
5.8 Define identifier. Give an example identifier for the entity in your answer to Review
Question 5.5.
I dentifiers are attributes that name, specify, locate (or otherwise identify) entity instances. For
example, in the Real
Estate Agency example in question 5.5. an identifier for the entity AGENT would be AgentID
5.10 Define relationship. Give an example of a relationship (other than one presented in this
chapter). Name your relationship.

5.15 What does cardinality mean?
5.16 Define the terms maximum cardinality and minimum cardinality.
5.17 Give examples of 1:1, 1:N, and N:M relationships (other than those presented in this
chapter). Draw two E-R diagrams for each of your examples, one using the traditional diamond
notation, and one using IE Crow’s Foot notation.
5.19 Give examples of M-M, M-O, O-M, and O-O relationships (other than those presented in
this chapter). Draw two E-R diagrams for each of your examples, one using the traditional
diamond notation, and one using IE Crow’s Foot notation.
In the Real Estate Agency each AGENT must use an agency car when on agency business.

In the Real Estate Agency. each CLIENT must be assigned to an AGENT, but there may be
AGENTs who currently have no CLIENTs. This is an M-O (same as O-M, but seen reversed)
relationship.