Q33

MCQ2 marks, −0.67

Consider a relational database schema with two relations $R(P, Q)$ and $S(X, Y)$ . Let $E=\{\langle u\rangle \mid \exists v \exists w\langle u, v\rangle \in R \wedge\langle v, w\rangle \in S\}$ be a tuple relational calculus expression. Which one of the following relational algebraic expressions is equivalent to $E$ ?

(A)

$\Pi_{P}\left(R \bowtie_{R . P=S . X} S\right)$

(B)

$\Pi_{P}\left(S \bowtie_{S . X=R . Q} R\right)$

(C)

$\Pi_{P}\left(R \bowtie_{R . P=S . Y} S\right)$

(D)

$\Pi_{P}\left(S \bowtie_{S . Y=R . Q} R\right)$

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