A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

81. Match the following database terms to their functions:

List-I                                       List-II
(a) Normalization                     (i) Enforces match of primary key to foreign key
(b) Data Dictionary                  (ii) Reduces data redundancy in a database
(c) Referential Integrity           (iii) Define view(s) of the database for particular user(s).
(d) External Schema               (iv) Contains metadata describing database structure.

Codes:
      (a)   (b)   (c)    (d)
a. (iv)   (iii)   (i)   (ii)
b. (ii)    (iv)   (i)   (iii)
c. (ii)   (iv)   (iii)   (i)
d. (iv)   (iii)   (ii)   (i)
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Answer: (b).(ii)    (iv)   (i)   (iii)

82. Which of the following provides the best description of an entity type?
a. A specific concrete object with a defined set of processes (e.g. Jatin with diabetes)
b. A value given to a particular attribute (e.g. height-230 cm)
c. A thing that we wish to collect data about zero or more, possibly real world examples of it may exist
d. A template for a group of things with the same set of characteristics that may exist in the real world
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Answer: (d).A template for a group of things with the same set of characteristics that may exist in the real world

83. Data which improves the performance and accessibility of the database are called:
a. Indexes
b. User Data
c. Application Metadata
d. Data Dictionary
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Answer: (a).Indexes

84. A relation R={A,B,C,D,E,F,G} is given with following set of functional dependencies:

F={AD→E, BE→F, B→C, AF→G}

Which of the following is a candidate key?
a. A
b. AB
c. ABC
d. ABD
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Answer: (d).ABD

85. The hash function used in double hashing is of the form:
a. (A) h(k, i)=(h1(k)+h2(k)+i)mod m
b. h(k, i)=(h1(k)+h2(k)-i)mod m
c. h(k, i)=(h1(k)+ih2(k))mod m
d. h(k, i)=(h1(k)-ih2(k))mod m
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Answer: (c).h(k, i)=(h1(k)+ih2(k))mod m

86. Which of the following statements regarding the features of the object-oriented approach to databases are true ?

(a) The ability to develop more realistic models of the real world.
(b) The ability to represent the world in a non-geometric way.
(c) The ability to develop databases using natural language approaches.
(d) The need to split objects into their component parts.
(e) The ability to develop database models based on location rather than state and behaviour.
a. (a), (b) and (c)
b. (b), (c) and (d)
c. (a), (d) and (e)
d. (c), (d) and (e)
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Answer: (a).(a), (b) and (c)

87. Consider the following database table :

Create table test(
one integer,
two integer,
primary key(one),
unique(two),
check(one≥1 and ≤10),
check(two≥1 and ≤5) );

How many data records/tuples atmost can this table contain ?
a. 5
b. 10
c. 15
d. 50
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Answer: (a).5

88. Suppose ORACLE relation R(A, B) currently has tuples {(1, 2), (1, 3), (3, 4)} and relation S(B, C) currently has {(2, 5), (4, 6), (7, 8)}. Consider the following two SQL queries SQ1 and SQ2 :

SQ1 : Select *
From R Full Join S
On R.B=S.B;
SQ2 : Select *
From R Inner Join S
On R.B=S.B;

The numbers of tuples in the result of the SQL query SQ1 and the SQL query SQ2 are given by :
a. 2 and 6 respectively
b. 6 and 2 respectively
c. 2 and 4 respectively
d. 4 and 2 respectively
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Answer: (d).4 and 2 respectively

89. Consider the following three SQL queries (Assume the data in the people table) :

(a) Select Name from people where Age>21;
(b) Select Name from people where Height>180;
(c) Select Name from people where (Age>21) or (Height>180);

If the SQL queries (a) and (b) above, return 10 rows and 7 rows in the result set respectively, then what is one possible number of rows returned by the SQL query (c) ?
a. 3
b. 7
c. 10
d. 21
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Answer: (c).10

90. Consider the following three tables R, S and T. In this question, all the join operations are natural joins (⨝). (π) is the projection operation of a relation. Possible answer tables for this question are also given as below.
What is the resulting table of πA,B(R⨝T) ⨝ πB,C(S⨝T) ?
a. (a)
b. (b)
c. (c)
d. (d)
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Answer: (a).(a)