ALTER TABLE reserves ADD FOREIGN KEY (sid) REFERENCES sailor (sid);
 ALTER TABLE reserves ADD FOREIGN KEY (bid) REFERENCES boat (bid);

-- NO 1
SELECT
    sname
FROM
    sailor,
    reserves
WHERE
    sailor.sid = reserves.sid AND reserves.bid = 103;
-- NO 2
SELECT
    sname
FROM
    sailor,
    reserves,
    boat
WHERE
    sailor.sid = reserves.sid AND boat.color = 'red' AND reserves.bid=boat.bid;
-- NO 3
SELECT color
FROM
    sailor,
    reserves,
    boat
 WHERE
    reserves.bid = boat.bid AND reserves.sid=sailor.sid AND sname='Lubber';
-- NO 4
SELECT sname
FROM
    sailor,
    reserves
GROUP BY
    sname
HAVING COUNT(*)>2
-- NO 5
SELECT sname
FROM
    sailor,
    reserves,
    boat
WHERE
    reserves.bid = boat.bid AND reserves.sid=sailor.sid AND boat.color = 'red';
UNION
SELECT sname
FROM
    sailor,
    reserves,
    boat
WHERE
    reserves.bid = boat.bid AND reserves.sid=sailor.sid AND boat.color = 'green';
-- NO 6
SELECT sname
FROM
    sailor,
    reserves,
    boat
WHERE
    reserves.bid = boat.bid AND reserves.sid=sailor.sid AND boat.color = 'red';
INTERSECT
SELECT sname
FROM
    sailor,
    reserves,
    boat
WHERE
    reserves.bid = boat.bid AND reserves.sid=sailor.sid AND boat.color = 'green';