Database Design(Normal Forms)

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Question 1

For the relation R(ABCDEFGH) with FD's= {CH->G, A->BC, B->CHF, E->A, F->EG such that F+ is exactly the set of FDs that hold for R.} Consider the FDs given in above question. The relation R is

  • in 1NF, but not in 2NF.

  • in 2NF, but not in 3NF.

  • in 3NF, but not in BCNF.

  • in BCNF

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Question 2

Which of the following is TRUE?
  • Every relation in 3NF is also in BCNF
  • A relation R is in 3NF if every non-prime attribute of R is fully functionally dependent on every key of R
  • Every relation in BCNF is also in 3NF
  • No relation can be in both BCNF and 3NF
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Question 3

Consider a relational table with a single record for each registered student with the following attributes. 
1. Registration_Num: Unique registration number
   of each registered student
2. UID: Unique identity number, unique at the 
   national level for each citizen
3. BankAccount_Num: Unique account number at
   the bank. A student can have multiple accounts
   or join accounts. This attribute stores the 
   primary account number.
4. Name: Name of the student
5. Hostel_Room: Room number of the hostel
Which one of the following option is INCORRECT?
  • BankAccount_Num is candidate key
  • Registration_Num can be a primary key
  • UID is candidate key if all students are from the same country
  • If S is a superkey such that S∩UID is NULL then S∪UID is also a superkey
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Question 4

Consider the following relational schema: 
Suppliers(sid:integer, sname:string, city:string, street:string)
Parts(pid:integer, pname:string, color:string)
Catalog(sid:integer, pid:integer, cost:real)
Assume that, in the suppliers relation above, each supplier and each street within a city has a unique name, and (sname, city) forms a candidate key. No other functional dependencies are implied other than those implied by primary and candidate keys. Which one of the following is TRUE about the above schema?
  • The schema is in BCNF
  • The schema is in 3NF but not in BCNF
  • The schema is in 2NF but not in 3NF
  • The schema is not in 2NF
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Question 5

Consider the following relational schemes for a library database: Book (Title, Author, Catalog_no, Publisher, Year, Price) Collection (Title, Author, Catalog_no) with in the following functional dependencies: 
I. Title Author --> Catalog_no
II. Catalog_no --> Title, Author, Publisher, Year
III. Publisher Title Year --> Price
Assume {Author, Title} is the key for both schemes. Which of the following statements is true?
  • Both Book and Collection are in BCNF
  • Both Book and Collection are in 3NF only
  • Book is in 2NF and Collection is in 3NF
  • Both Book and Collection are in 2NF only
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Question 6

Consider the relation scheme R = {E, F, G, H, I, J, K, L, M, N} and the set of functional dependencies {{E, F} -> {G}, {F} -> {I, J}, {E, H} -> {K, L}, K -> {M}, L -> {N} on R. What is the key for R?

  • {E, F}

  • {E, F, H}

  • {E, F, H, K, L}

  • {E}

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Question 7

Given the following two statements: 
  S1: Every table with two single-valued 
      attributes is in 1NF, 2NF, 3NF and BCNF.

  S2: AB->C, D->E, E->C is a minimal cover for 
      the set of functional dependencies 
      AB->C, D->E, AB->E, E->C.
Which one of the following is CORRECT?
  • S1 is TRUE and S2 is FALSE.
  • Both S1 and S2 are TRUE.
  • S1 is FALSE and S2 is TRUE.
  • Both S1 and S2 are FALSE.
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Question 8

The maximum number of superkeys for the relation schema R(E,F,G,H) with E as the key is
  • 5
  • 6
  • 7
  • 8
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Question 9

Given the STUDENTS relation as shown below. 

 

For (StudentName, StudentAge) to be the key for this instance, the value X should not be equal to

  • 18

  • 19

  • 17

  • 20

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Question 10

Which one of the following statements about normal forms is FALSE?
  • BCNF is stricter than 3NF
  • Lossless, dependency-preserving decomposi­tion into 3NF is always possible
  • Lossless, dependency-preserving decomposi­tion into BCNF is always possible
  • Any relation with two attributes is in BCNF
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