Q15

MSQ1 mark

Consider the following three relations in a relational database. $\text{Employee} (\underline{\text{eId}},\text{Name}), \; \text{Brand}(\underline{\text{bId}},\text{bName}), \; \text{Own}(\underline{\text{eId}},\underline{\text{bId}})$ Which of the following relational algebra expressions return the set of $\textit{elds}$ who own all the brands?

(A)

$\Pi_{eId} \left(\Pi_{eId,bId} (Own) / \Pi_{bId} (Brand) \right)$

(B)

$\Pi_{eId} (Own) – \Pi_{eId} \left( ( \Pi_{eId} (Own) \times \Pi_{bId} (Brand)) – \Pi_{eId,bId} (Own)\right)$

(C)

$\Pi_{eId} \left(\Pi_{eId,bId} (Own) / \Pi_{bId} (Own) \right)$

(D)

$\Pi_{eId} \left( (\Pi_{eId}(Own) \times \Pi_{bId} (Own)) / \Pi_{bId} (Brand) \right)$

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