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Unformatted text preview: (donations) ´ ρ B (donations)] b) { < N > | ∀ x ( <r , x, tobacco, s > ∈ donations ⇒ <N , x, tobacco, t > ∈ donations) } (3 points) Recipients who received donations from every tobacco donor organization. π recipientName, donorOrganization(donations) / π donorOrganization (σ organizationType = tobacco (donations)) c) { < N > | ∃ x (<N, r, tobacco, x> ∈ donations and ∀ y ( <s, t, tobacco, y> ∈ donations ⇒ x ≥ y) } (4 points) Short version: Recipients who received the highest donation amount from a tobacco company.[note; this English version isn’t entirely precise, because it could be interpreted “for each company”, which isn’t what we mean. See the Relational Algebra for an exact comparison] π recipientName (σ organizationType = tobacco (donations)) – π A.recipientName (σ A.organizationType = tobacco and B.organizationType = tobacco and A.amount < B.amount [ρ A (donations) ´ ρ B (donations)] ) d) (Removed fro m the exam.) Questio...
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This document was uploaded on 03/18/2014 for the course CPSC 304 at University of British Columbia.

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