Yurttas/PL/DBL/mysql/F/01/00/PC/q18.sql

 1/*
 2REM
 3REM q18.sql
 4REM
 5REM Find the manufacturers who sell exactly three different
 6REM models of PC.
 7REM
 8*/
 9
10\. set-db.sql
11
12SELECT P.maker
13FROM Product P, PC
14WHERE P.model=PC.model
15GROUP BY P.maker
16HAVING COUNT(DISTINCT PC.model)=3;