$6\mathrm{.}3.$ SUBQUERIES

$6\mathrm{.}3\mathrm{.}9$ Exercises for Section $6\mathrm{.}3$

Exercise $6\mathrm{.}3\mathrm{.}1$: Write the following queries, based on the database schema

Product$(maker,$ model, type$)$

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

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

Printer$(model,$ color, type, price$)$

of Exercise $2\mathrm{.}4\mathrm{.}1.$ You should use at least one subquery in each of your answers

and write each query in two significantly different ways $($e$.$g$.,$ using different

sets of the operators EXISTS, IN$,$ ALL, and ANY$).$

a$)$ Find the makers of PC$\text{'}$s with a speed of at least $3\mathrm{.}0.$

b$)$ Find the printers with the highest price.

$!$ c$)$ Find the laptops whose speed is slower than that of any PC$.$

$!$d$)$ Find the model number of the item $($PC$,$ laptop, or printer$)$ with the

highest price.

$!$e$)$ Find the maker of the color printer with the lowest price.

$!!$ f$)$ Find the maker$($s$)$ of the $PC(s)$ with the fastest processor among all those

PC$\text{'}$s that have the smallest amount of RAM.

Exercise $6\mathrm{.}3\mathrm{.}2$ : Write the following queries, based on the database schema

Classes$(class,$ type, country, numGuns, bore, displacement$)$

Ships$(name,$ class, launched$)$

Battles$(name,$ date$)$

Outcomes$(ship,$ battle, result$)$

of Exercise $2\mathrm{.}4\mathrm{.}3.$ You should use at least one subquery in each of your answers

and write each query in two significantly different ways $($e$.$g$.,$ using different

sets of the operators EXISTS, IN$,$ ALL, and ANY$).$

a$)$ Find the countries whose ships had the largest number of guns.

$!$b$)$ Find the classes of ships, at least one of which was sunk in a battle.

c$)$ Find the names of the ships with a $16-$inch bore.

d$)$ Find the battles in which ships of the Kongo class participated.

$!!$ e$)$ Find the names of the ships whose number of guns was the largest for

those ships of the same bore.