Monday, 9 March 2015

Normalization and Functional Dependency - Quiz

Normalization and Functional Dependency - Quiz


1. A relationship R connecting entity sets E and F has referential integrity from E to F, i.e., the edge connecting R and F has an arrow directed towards F. Which of the following statements may be true?
    R is one-one from E to F
    R is many-one from E to F
    Choice 2 only
    Both choices 1 and 2

2. A relation with two attributes A and B satisfies the functional dependency A → B. Then the functional dependency B → A also holds in the relation.
    TRUE
    FALSE

3. A relation R(A,B,C) satisfies the functional dependencies A → B, A → C, and B → A. Then, we can say that R is in BCNF.
    TRUE
    FALSE

4. A relation R(A,B,C) satisfies the functional dependencies A → B, A → C, and B → A. Which of the following are valid candidate keys?
    A
    B
    Both choices 1 and 2
    A alone

5. Which of the following sentences are true??
    4NF implies BCNF
    4NF implies 3NF
    3NF implies 4NF
    Both choices 1 and 2

6. Assume that we have the following four records in a relation R(A, B, C): (1,2,3), (4,2,3), (5,3,3), and (5,3,4). Which of the following FDs does not hold on R?
    BC → A
    B → C
    C → B
    All of the above

7. For a relation R1(A,C,B,D,E), with dependencies A → B, and C → D which of the following is the candidate key?
    {ABC}
    {ACE}
    {ADE}
    {ABE}

8. The closure of set of attributes is said to be a set of ____________.
    Functional Dependencies
    Attributes
    Keys
    Multivalued Attributes

9. {A1, A2, …, An}+ is the set of all attributes of R if and only if A1, A2, …, An is a _______________ for R.
    Prime attribute
    Closure attributes
    Super key
    All of the above

10. Assume that the following set of FDs A → B, B → C, C → A, D → E, E → D are holding on a relation R(A,B,C,D,E). Which of the following sets of tuples satisfy this.
    a1 b1 c1 d1 e1, a1 b1 c1 d2 e2
    a1 b1 c1 d1 e1, a1 b2 c1 d2 e2
    a1 b1 c1 d1 e2, a1 b1 c1 d2 e2
    None of the above

Score =

Correct answers:

2 comments:

  1. Can you give an explanation for the 6th question?

    ReplyDelete
    Replies
    1. Each set of values is a row(record). BC-->A is not true because for third and fourth records 5,3 --> 3 and 5, 3 --> 4. Likewise please check for other FDs.

      Delete

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