Q41

MCQ2 marks, −0.67

Consider the relations $r(A, B)$ and $s(B, C)$ , where $s.B$ is a primary key and $r.B$ is a foreign key referencing $s.B$ . Consider the query $Q: r \bowtie (\sigma_{B<5} (s))$ Let LOJ denote the natural left outer-join operation. Assume that $r$ and $s$ contain no null values. Which of the following is NOT equivalent to $Q$ ?

(A)

$\sigma_{B<5} (r \bowtie s)$

(B)

$\sigma_{B<5} (r \: LOJ \: s)$

(C)

$r \: LOJ \: (\sigma_{B<5} (s))$

(D)

$\sigma_{B<5} (r) \: LOJ \: s$

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