WB JECA MCA Database Management Systems Previous Year Questions (PYQs) – Page 2 of 3
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Showing 26 questions
There is a possibility of a cascading rollback when
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Solution
Dirty read/write leads to cascading rollback.
In an entity relationship, y is the dominant entity and x is a subordinate entity. Then which one is incorrect?
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Solution
Deleting subordinate does not affect dominant.
Choose the correct statement:
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Solution
Alternate key = candidate key not chosen as primary.
If one attribute is a determinant of a second, which in turn is a determinant of a third, then the relation cannot be
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Solution
Transitive dependency violates 3NF.
Which of the following statements regarding relational algebra are true?
(i) R ⋈ S = σ(R×S)
(ii) R ⋈ S = Π(R×S)
(iii) R ⋈ S = R * S
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Solution
Join is selection over cartesian product.
Relational calculus is a
(A) Procedural language
(B) Non-procedural language
(C) Data definition language
(D) High-level language
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Solution
- Relational Algebra is procedural (it specifies how to obtain the result).
- Relational Calculus is non-procedural (it specifies what to obtain, not how).
Correct Answer: (B) Non-procedural language
Which of the following should not have transitive dependency?
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Solution
Solution:
- 3NF (Third Normal Form) removes transitive dependency.
- Hence, it should not have transitive dependency.
Answer = (C) Third normal form
- 3NF (Third Normal Form) removes transitive dependency.
- Hence, it should not have transitive dependency.
Answer = (C) Third normal form
The physical relationship of record is determined by a mathematical formula that transforms a file key into a record location in
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Solution
A mathematical formula that maps a key directly to a storage location is called a hash function. This is used in hashed files.
In an ER diagram, an entity set is represented by a
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Solution
Solution: Entity sets are rectangles; Attributes = ellipses; Relationships = diamonds.
Answer: (A) Rectangle
Answer: (A) Rectangle
Given an unsorted array where each element is at most k distance from its position in a sorted array. Which sorting algorithm can be easily modified for this and what is its time complexity?
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Solution
Solution: A k-sorted array can be efficiently sorted using a min-heap of size k, yielding O(n log k) time.
Answer: (B) Heap Sort with O(n log k)
Answer: (B) Heap Sort with O(n log k)
WB JECA MCA
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