3. Quiz Questions
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3. Quiz Questions

3.1. Question 1: Table populations of bidirectional associations

Consider the following table pairs representing the populations of the classes A and B where the columns A::id and B::id are primary keys and A::b_id and B::a_id are foreign keys referencing B, respectively A.

In which of the following cases does the property pair A::b_id and B::a_id implement a bidirectional association? Select one or more:

  1. ☐

    A B
    id b_id
    1 2
    2 1
    3 3
    id a_id
    1 2
    2 1
    3 3

  2. ☐

    A B
    id b_id
    1 3
    2 1
    3 2
    id a_id
    1 1
    2 3
    3 2

  3. ☐

    A B
    id b_id
    1 3
    2 1
    3 2
    id a_id
    1 2
    2 3
    3 1

  4. ☐

    A B
    id b_id
    1 3
    2 3
    3 2
    id a_id
    1 2
    2 3
    3 1

3.2. Question 2: Implications of bidirectionality

Representing a bidirectional association with a pair of mutually inverse reference properties implies (select one or many):

  1. ☐ information redundancy

  2. ☐ slower read access

  3. ☐ data storage overhead

  4. ☐ update overhead

  5. ☐ faster updates

  6. ☐ more efficient data storage requiring less memory

  7. ☐ efficient object access in both directions

3.3. Question 3: Elimination of bidirectional associations

Consider the following information design model with a bidirectional association between the classes Aa and Bb.

Which of the following OO class models are correct representations of this model? Select one or more:

  1. ☐

  2. ☐

  3. ☐

  4. ☐

3.4. Question 4: Meaning of bidirectional association

A bidirectional association Committee-isChairedBy-ClubMember between the classes Committee and ClubMember corresponds to ... (select one or more):

  1. ☐ A pair of reference properties Committee::chair and ClubMember::chairedCommittee such that Committee::chair is the inverse of ClubMember::chairedCommittee and ClubMember::chairedCommittee is the inverse of Committee::chair.

  2. ☐ A pair of reference properties Committee::chair and ClubMember::chairedCommittee.

  3. ☐ A pair of reference properties Committee::chair and ClubMember::chairedCommittee such that Committee::chair is the inverse of ClubMember::chairedCommittee.

  4. ☐ A pair of reference properties Committee::chair and ClubMember::chairedCommittee such that ClubMember::chairedCommittee is the inverse of Committee::chair.

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