Yurttas/PL/DBL/oracle/F/01/PC/q11.sql
1REM
2REM q11.sql
3REM
4REM Find the average hard disk size of a PC for all those
5REM manufacturers that make printers.
6REM
7
8SELECT P.maker, AVG(hd)
9FROM Product P, PC
10WHERE P.model=PC.model
11 AND P.maker IN (SELECT P.maker
12 FROM Product P, Printer R
13 WHERE P.model=R.model)
14GROUP BY P.maker;