Yurttas/PL/DBL/oracle/F/01/Company-B/q08.sql

 1REM
 2REM q08.sql
 3REM
 4REM Assume the companies may be located in several cities.
 5REM Find all companies located in every city in which
 6REM 'Small Bank Corporation' is located.
 7REM
 8
 9SELECT DISTINCT C1.companyname 
10FROM Company C1
11WHERE NOT EXISTS
12            (SELECT city 
13             FROM Company 
14             WHERE companyname='Small Bank Corporation' 
15               AND city NOT IN (SELECT C2.city 
16                                FROM Company C2 
17                                WHERE C1.companyname = C2.companyname)) 
18  AND C1.companyname <> 'Small Bank Corporation';