--Simple sample query
select p.PASSENGERNUM, p.PASSENGERNAME, COUNT(cruisenum)
from Passenger as p, Voyage as v
where p.PASSENGERNUM = v.PASSENGERNUM
group by p.PASSENGERNUM, PASSENGERNAME
having count(cruisenum) > 1
--Query Designer example
select * from Ship
SELECT Passenger.PASSENGERNUM, Passenger.PASSENGERNAME, Ship.SHIPNAME
FROM Passenger INNER JOIN
Voyage ON Passenger.PASSENGERNUM = Voyage.PASSENGERNUM INNER JOIN
Cruise ON Voyage.CRUISENUM = Cruise.CRUISENUM INNER JOIN
Ship ON Cruise.SHIPNUM = Ship.SHIPNUM
WHERE (Ship.SHIPNAME = 'Prince Al')
--Give pairs of ships where the builder is the same and the weight is different by more than 10000
select s1.SHIPNAME, s1.WEIGHT, s1.BUILDER, s2.SHIPNAME, s2.WEIGHT
from Ship as s1, ship as s2
where s1.BUILDER=s2.BUILDER
and (s1.WEIGHT-s2.WEIGHT) > 10000