Yurttas/PL/DBL/mssql/F/01/PC/q16.sql

 1/*
 2REM
 3REM q16.sql
 4REM
 5REM Find those pairs of PC models that have both
 6REM the same speed and RAM. A pair should be listed only once;
 7REM e.g., list(i,j) but not (j,i).
 8REM
 9*/
10
11SELECT DISTINCT P1.model, P2.model
12FROM PC P1, PC P2
13WHERE P1.ram=P2.ram
14  AND P1.speed=P2.speed
15  AND P1.model>P2.model;