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.

21. Division operation is ideally suited to handle queries of the type :
a. customers who have no account in any of the branches in Delhi
b. customers who have an account at all branches in Delhi
c. customers who have an account in at least one branch in Delhi
d. customers who have only joint account in any one branch in Delhi
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Answer: (b).customers who have an account at all branches in Delhi

22. What kind of mechanism is to be taken into account for converting a weak entity set into strong entity set in entity-relationship diagram?
a. Generalization
b. Aggregation
c. Specialization
d. Adding suitable attributes
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Answer: (d).Adding suitable attributes

23. Which of the following is true?

I.  Implementation of self-join is possible in SQL with table alias.

II. Outer-join operation is basic operation in relational algebra.

III. Natural join and outer join operations are equivalent.
a. I and II are correct
b. II and III are correct
c. Only III is correct
d. Only I is correct
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Answer: (d).Only I is correct

24. Which of the following is correct?

I. Two phase locking is an optimistic protocol.
II. Two phase locking is pessimistic protocol
III. Time stamping is an optimistic protocol.
IV. Time stamping is pessimistic protocol.
a. I and III
b. II and IV
c. I and IV
d. II and III
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Answer: (c).I and IV

25. ________________rules used to limit the volume of log information that has to be handled and processed in the event of system failure involving the loss of volatile information.
a. Write-ahead log
b. Check-pointing
c. Log buffer
d. Thomas
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Answer: (b).Check-pointing

26. Let R = ABCDE is a relational scheme with functional dependency set F = {A -> B, B ->C,AC -> D}. The attribute closures of A and E are
a. ABCD, Ø
b. ABCD, E
c. ɸ , Ø
d. ABC, E
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Answer: (b).ABCD, E

27. Consider the following statements:

I. Re-construction operation used in mixed fragmentation satisfies commutative rule.
II. Re-construction operation used in vertical fragmentation satisfies commutative rule
Which of the following is correct?
a. I
b. II
c. Both are correct
d. None of the statements are correct
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Answer: (b).II

28. Which of the following is false?
a. Every binary relation is never be in BCNF
b. Every BCNF relation is in 3NF
c. 1 NF,2 NF, 3 NF and BCNF are based on functional dependencies
d. Multivalued Dependency (MVD) is a special case of Join Dependency (JD)
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Answer: (c).1 NF,2 NF, 3 NF and BCNF are based on functional dependencies

29. An Assertion is a predicate expressing a condition we wish database to always satisfy. The correct syntax for Assertion is :
a. CREATE ASSERTION',ASSERTION Name', CHECK',Predicate',
b. CREATE ASSERTION 'ASSERTION NAME'
c. CREATE ASSERTION, CHECK Predicate
d. SELECT ASSERTION
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Answer: (a).CREATE ASSERTION',ASSERTION Name', CHECK',Predicate',

30. Which of the following concurrency protocol ensures both conflict serializability and freedom from deadlock ?

(a) 2-phase Locking
(b) Time stamp - ordering
a. Both (a) and (b)
b. (a) only
c. (b) only
d. Neither (a) nor (b)
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Answer: (c).(b) only

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