Problem 10 Consider the ER-diagram for the MOVIES database in the figure below.

Question

Problem 10 Consider the ER-diagram for the MOVIES database in the figure below. Assume that MOVIES is a populated database. ACTOR is used as a generic term and includes actresses. Given the constraints shown in the ER schema, respond to the following statements with True, False, or Maybe. Assign a response of Maybe to statements that, while not explicitly shown to be True, cannot be proven False based on the schema as shown. Justify each answer (otherwise you will not be given any credit!). MOVME ACTOR ALSO A. DIRECTOR ACTOR PRODUCER DIRECTOR DIRECTS a) There are no actors in this database that have been in no movies. (1 point) b) There are some actors who have acted in more than ten movies. (1 point) c) A movie can have only a maximum of two lead actors. d) Every director has been an actor in some movie. e) No producer has ever been an actor. f) There are movies with more than a dozen actors. g) Most movies have one director and one producer. h) No movie has a director who also acted in that movie. (1 point) (1 point) (1 point) (1 point) (1 point) (1 point)

Explanation / Answer

a. True.

because the actor and the movies are in m:n relationship and hence any actor can act in any no. of movies and the Double lines denote the complete participation.

b.May be

Again since the actor and the movie entities are in M:N relationship, it depends on the value of N.

c.True

If we the cardinality in the relation "LEAD_ROLE", it shows that a movie can have only maximum 2 lead actors where as an actor can perform a lead role in many movies.

d. False

Given that there is a partial participation in the relation "ALSO_A_DIRECTOR", it shows that there might be some directors who have not been acted in any movie.

e.False.

There exits a relation between the producer entity and the Actor entity named as "ACTOR_PRODUCER". It shows the partial participation of both the entities in the relation. So there might be some producer who are also actors.

f.May be

As said for the question 2, it depends on the values of m and n.

g.May be

The M:N reation between the producer states that there can be more than one producer for a given movie. But the givne the statement starting with 'most', it states it might be an assumption.

h.False.

There can be a possibility as the partial particpation of the Director entity exists in both ALSO_A_ACTOR and DIRECTS relations.

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