assignment4_solution

# assignment4_solution - Assignment#4 Solution EECS 341 Fall...

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Assignment #4 Solution EECS 341 Fall 2015 Due 3PM Wednesday Oct 28 2015 1. Consider the following schema: Suppliers (sid, sname, address) Parts (pid, pname, color) Catalog (sid, pid, cost) Write the following queries in relational algebra. 1. (15 points) Find the names of suppliers who supply some red part. 2. (15 points) Find the sids of suppliers who supply some red part or are at 123 Parker Street. 3. (15 points) Find the sids of suppliers who supply every part. 4. (15 points) Find the sids of suppliers who supply every red or green part. 5. (20 points) Find pairs of sids such that the supplier with the first sid charges more for some part than the supplier with the second sid. 6. (20 points) Find the pids of the most expensive parts supplied by suppliers named AllMedcialSuppliers. Solution: Note: alternative answers are allowed. (1) {<sn>| ∃s , a (<s, sn, a> ϵ Suppliers ˄ ∃p, c (<s, p, c> ϵ Catalog ˄ pn, cl (<p, pn, cl> ϵ Part s ˄ cl =” red )))} (2) {<s>| ∃p, c (<s, p, c> ϵ Catalog ˄ pn, cl (<p, pn, cl> ϵ Part s ˄ cl =” red )) ˅ ∃sn , a (<s, sn, a> ϵ

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