Yurttas/PL/DBL/mysql-f-2010/01/PC/q06.sql

 1/*
 2REM
 3REM q06.sql
 4REM
 5REM Find those manufacturers of at least two different
 6REM computers (PC's or laptops) with speeds of at least 133.
 7REM
 8*/
 9
10\. set-db.sql
11
12SELECT maker
13FROM Product
14WHERE model IN ( (SELECT P.model
15                  FROM Product P, PC
16                  WHERE P.model=PC.model
17                    AND PC.speed>=133)
18                  UNION
19                 (SELECT P.model
20                  FROM Product P, Laptop L
21                  WHERE P.model=L.model
22                    AND L.speed>=133) )
23GROUP BY maker
24HAVING COUNT(model)>=2;