Section 4
(Answer all questions in this section)

  1. All instances of the supertype are also instances of one of the subtypes. True or False?

  True 

False



  2. All instances of the subtypes must be an instance of the supertype. True or False?

  True 

False



  3. Which of the following is true about supertypes and subtypes?

Instances that belong to two subtypes of the same supertype may be modeled as a one-to-one relationship between the two subtypes

  Subtypes inherit the relationships and attributes of the supertype. 

Subtypes may have no more than 2 levels of nesting.

Supertype and subtype entities must be mutually exclusive



4. Which of the following is a TRUE statement about the diagram below?
  
Every Z is either an A or a B

Every B is a Z

Every A is a Z

  Every A is a B 



  5. A subtype can have a relationship not shared by the supertype. True or False?

  True 

False



  6. A supertype should have at least two subtypes. True or False?

  True 

False




  7. Which of the following is the best scenario for using supertype/subtype entities:

A pet store that sells small animals, because they each need different size cages and food.

An ice cream store that sells ice cream in sugar cones and regular cones.

A grocery store that gives customers a choice of plastic or paper bags.

  A vehicle dealership that sells cars, trucks and boats on trailers. 



  8. The "Other" subtype is best used:

For instances that belong to the supertype and at least one other subtype.

For a subtype that does not have any of the same attributes as the supertype to which it belongs.

  As an extra subtype to ensure that all instances of subtypes are mutually exclusive and complete. By having an "Other" subtype, all instances of the Supertype will be of one subtype type. 

You should never have a subtype called Other.