Yurttas/PL/DBL/oracle/F/01/PC/q07.sql

 1REM
 2REM q07.sql
 3REM
 4REM Find the manufacturer(s) of the computer(PC or laptop)
 5REM with the highest available speed.
 6REM
 7
 8CREATE VIEW ProdSpeed(model, speed)
 9  AS (SELECT model, speed
10      FROM PC
11      WHERE speed IN (SELECT MAX(speed)
12                      FROM  PC))
13     UNION
14     (SELECT model, speed
15      FROM Laptop
16      WHERE speed IN (SELECT MAX(speed)
17                      FROM  Laptop));
18
19SELECT P.maker, S.speed
20FROM Product P, ProdSpeed S
21WHERE P.model=S.model
22  AND S.speed IN (SELECT MAX(speed)
23                  FROM ProdSpeed);