Given the ERD below which of the following relational designs is appropriate? (T

Question

Given the ERD below which of the following relational designs is appropriate? (The primary key is underlined and the foreign key is in italics in the answers.) AGENT ACTOR Represented By AgentID ActorID FirstName FirstName LastName LastName REPRESENTS AGENT entl D, LastName, FirstName) ACTOR (Actor LastName, FirstName AGENT ACTOR. (AgentlD, ActorD O AGENT (Agentl D, LastName, First Name ACTOR (Actor DI LastName, FirstName O AGENT entl D, LastName, FirstName) ACTOR (ActorlD, LastName, FirstName, Agent fD) O AGENT entl D, LastName, FirstName) ACTOR (Actorl D, LastName, FirstName) O AGENT entl D, LastName, FirstName) ACTOR (ActorlD, LastName, FirstName) AGENT ACTOR. (Agent f0, ActorfD) O AGENT entl DI LastName, First Name, Actor ACTOR (ActorlD, LastName, FirstName)

Explanation / Answer

Question 16:

AGENT(AgentID,LastName,FirstName)

ACTOR(ActorID,LastName,FirstName)

AGENT_ACTOR(AgentID,ActorID)
Explaination: Agent and Actor relations hold information about the self, Agent Actor relation holds information about the relation between both tables,

1. Agent represents Actor and Actor is represented by Agent, hence keys need to be present in both tables.

2. To have normalized relation, there is separate relation for this.

3. They have IDs from Agent and Actor, they should be foreign keys

Question 17:

Option: The foreign key must be unique but a value is not required for every row

Explaination: Species member can have maximum one but may not have any mate at all (thus value can be NULL)

Species member cannot be mate to more than one species (thus unique)

Question 18. The foreign key must be unique but a value is not required for every row

Explaination: One to one relationship hence, unique. License can be null for a Person, thus value not required for each row

Question 19. The foreign key will not require unique value but a value is required for every row.

Explaination: as the relationship diagram suggest, many to many relationship, but value is must

Question 20. The foreign key will not require unique value but a value is required for every row.

Explaination: as the relationship diagram suggest, many to many relationship, but value is must

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