Questions & Answers of Integrity Constraints, Normal Forms

Question No. 16

The following functional dependencies hold true for the relational schema R {V, W, X, Y, Z}:

                                                                                $\style{font-family:'Times New Roman'}{\begin{array}{l}V\rightarrow W\\VW\rightarrow X\\Y\rightarrow VX\\Y\rightarrow Z\end{array}}$

Which of the following  is irreducible equivalent  for this  set of functional dependencies ?

Question No. 119

Consiider the following tables T1 and T2

T1
P Q
2 2
3 8
7 3
5 8
6 9
8 5
9 8
T2
R S
2 2
8 3
3 2
9 7
5 7
7 2

In table T1, P is the primary key and Q is the foreign key referencing R in table T2 with on-delete cascabe and on-update cascade. In table T2, R is the primary key and S is the forign key refrencing P in table T1 with on-delete set NULL and ON-update cascade. In order to delete record <3,8> from table T1, the number of additional records that need to be deleted from table T1 is _____________________.

Question No. 33

A database of research articles in a journal uses the following schema.
     (VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, YEAR, PRICE)
The primary key is (VOLUME, NUMBER, STARTPAGE, ENDPAGE) and the following functional dependencies exist in the schema.
     (VOLUME, NUMBER, STARTPAGE, ENDPAGE) → TITLE
     (VOLUME, NUMBER) → YEAR
     (VOLUME, NUMBER, STARTPAGE, ENDPAGE) → PRICE
The database is redesigned to use the following schemas.
   (VOLUME, NUMBER, STARTPAGE, ENDPAGE, TITLE, PRICE)
   (VOLUME, NUMBER, YEAR)
Which is the weakest normal form that the new database satisfies, but the old one does not?

Question No. 213

Consider the relation X(P, Q, R, S, T, U) with the following set of functional dependencies

F = {
          {P, R} → {S, T},
          {P, S, U} → {Q, R}
      }

Which of the following is the trivial functional dependency in F+, where F+ is closure of F?

Question No. 31

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 ?

Question No. 40

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?

Question No. 131

The maximum number of superkeys for the relation schema R(E,F,G,H) with E as the key is _____.

Question No. 232

A prime attribute of a relation scheme R is an attribute that appears

Question No. 15

An index is clustered, if

Question No. 54

Relation R has eight attributes ABCDEFGH. Fields of R contain only atomic values. F={CH→G, A→BC, B→CFH, E→A, F→EG} is a set of functional dependencies (FDs) so that F+ is exactly the set of FDs that hold for R.
How many candidate keys does the relation R have?

Question No. 55

Relation R has eight attributes ABCDEFGH. Fields of R contain only atomic values. F={CH→G, A→BC, B→CFH, E→A, F→EG} is a set of functional dependencies (FDs) so that F+ is exactly the set of FDs that hold for R.

The relation R is

Question No. 2

Which of the following is TRUE?

Question No. 43

The following functional dependencies hold for relations R(A, B, C) and S(B, D, E)
B A,
A C
The relation R contains 200 tuples and the relation S contains 100 tuples. What is the maximum number of tuples possible in the natural join R $\bowtie$ S ?

Question No. 69

Consider the following relational schemes for a library database:
Book (Title, Author, Catalog_no, Publisher,Year,Price)
Collection (Title, Author, Catalog_no)
with 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 bot schemes.Which of the following statements is true?

Question No. 62

Which one of the following statements is FALSE?