Q30

MCQ1 mark, −0.25

Consider the following SQL query Select distinct $a_1, a_2, …, a_n$ from $r_1, r_2, …, r_m$ where P For an arbitrary predicate P, this query is equivalent to which of the following relational algebra expressions?

(A)

$\Pi_{a_1, a_2, … a_n} \sigma_p \left(r_1 \times r_2 \times \dots \times r_m\right)$

(B)

$\Pi_{a_1, a_2, … a_n} \sigma_p \left(r_1 \bowtie r_2 \bowtie \dots \bowtie r_m \right)$

(C)

$\Pi_{a_1, a_2, … a_n} \sigma_p \left(r_1 \cup r_2 \cup \dots \cup r_m \right)$

(D)

$\Pi_{a_1, a_2, … a_n} \sigma_p \left(r_1 \cap r_2 \cap \dots \cap r_m \right)$

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