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MCQs on Relational Algebra and Calculus - DBMS Objective Questions with Answers

Questions
16 The JOIN operator can be specified as :
A R x S
B σ(condition)(R x S)
C Both [A] and [B]
D None of these

Answer: Option [C]
17 The expression (R ∪ S)-((R-S) ∪ (S-R)) is equivalent to
A R/S
B R ∩ S
C σ(condition)(R x S)
D ∏(R x S)

Answer: Option [A]
18 If P and Q are predicates and P is the relational algebra expression, then which of the following equivalences are valid ?
A σPQ(e))=σQP(e))
B σPQ(e))=σQ(e)
CQP(e))=σQP(e))
D none of these

Answer: Option [D]
19 Which one is not a version of JOIN ?
A Equi join
B Outer join
C Natural join
D All are versions of JOIN

Answer: Option [D]
20 Relational calculus is :
I. equivalent to relational algebra in its capabilities.
II. it is stronger than relational algebra.
III. it is weaker than relational algebra.
IV. it is based on predicate calculus of formal logic.

Now answer which one is correct option ?

A (I) and (IV) are true
B (II) and (IV) are true
C only (III) is true
D (III) and (IV) are true

Answer: Option [D]

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