Exercise 6.2.3: 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 2.4.3, and evaluate your queries using the data of that exercise.

a) Find the ships heavier than 35,000 tons.

b) List the name, displacement, and number of guns of the ships engaged in the battle of Guadalcanal.

c) List all the ships mentioned in the database. (Remember that all these ships may not appear in the Ships relation.)

d) Find those countries that have both battleships and battlecruisers.

e) Find those ships that were damaged in one battle, but later fought in another.