EXERCISE 2.3.1:

create table Product (

maker char(255),

model number,

typex char(255)

);

create table PC (

model number,

speed number,

ram number,

hd number,

price number

);

create table Laptop (

Model number,

speed number,

ram number,

hd number,

screen number,

price number

);

create table Printer (

Model number,

color number,

typex char(255)

price number

);

Exercise 7.1.3: Suggest suitable keys and foreign keys for the relations of the PC database Product (maker, mode1, type) PC(model, speed, ram, hd, price) Laptop(model, speed, ram, hd, screen, price) Printer (model, color. type, price) of Exercise 2.4.1. Modify your SQL schema from Exercise 2.3.1 to include declarations of these keys