GATE Papers >> CSE >> 2009 >> Question No 55

Consider the following relational schema:

Suppliers(sid:integer, sname:string, city:string, street:string)
Parts(pid:integer, pname:string, color:string)
Catalog(sid:integer, pid:integer, cost:real)

Consider the following relational query on the above database:

SELECT S.sname
FROM Suppliers S
WHERE S.sid NOT IN (SELECT C.sid
                                FROM Catalog C
                                WHERE C.pid NOT (SELECT P.pid
                                                            FROM Parts P
                                                            WHERE P.color<> 'blue'))

Assume that relations corresponding to the above schema are not empty. Which one of the following is the correct interpretation of the above query?

• (A)  Find the names of all suppliers who have supplied a non-blue part.   
• (B)  Find the names of all suppliers who have not supplied a non-blue part.   
• (C)  Find the names of all suppliers who have supplied only blue parts.   
• (D)  Find the names of all suppliers who have not supplied only blue parts.