2.5.1

D)

Product(maker, model, type)

PC(model, speed, ram, hd, price)

Laptop(model, speed, ram, hd, screen, price)

Printer(model, color, type, price)

1) Show the Tuples that don't satisfy to the following constraint: A manufacturer of a PC must also make a laptop with at least as great a processor speed.

This is how far I got, with this constraint I get only B as answer. But im supposed to get B,C and D.

Select N.Maker From ((Select PR1.Maker,Min(PC.Speed) as Q1 From Product PR1 Inner Join PC On PR1.Model=PC.Model Group by PR1.Maker) as Q3,

(Select PR2.Maker, Max(Laptop.Speed) as Q2 From Product PR2 Inner Join Laptop On PR2.Model=Laptop.Model Group by PR2.Maker) as Q4) as N

Where Q3.Maker = Q4.Maker AND Q1 > Q2