test_database/pilot_1/sql.txt

/*** Division with a remainder */
SELECT DISTINCT pilot_name
  FROM PilotSkills AS PS1
  WHERE NOT EXISTS
       (SELECT *
          FROM Hangar
         WHERE NOT EXISTS
               (SELECT *
                  FROM PilotSkills AS PS2
                 WHERE (PS1.pilot_name = PS2.pilot_name)
                   AND (PS2.plane_name = Hangar.plane_name)));

/* alternatively */
SELECT PS1.pilot_name
   FROM PilotSkills AS PS1, Hangar AS H1
  WHERE PS1.plane_name = H1.plane_name
  GROUP BY PS1.pilot_name
  HAVING COUNT(PS1.plane_name) = (SELECT COUNT(plane_name) FROM Hangar);

/* Exact division */
SELECT PS1.pilot_name
  FROM PilotSkills AS PS1
       LEFT OUTER JOIN
       Hangar AS H1
       ON PS1.plane_name = H1.plane_name
  GROUP BY PS1.pilot_name
HAVING COUNT(PS1.plane_name) = (SELECT COUNT(plane_name) FROM Hangar)
   AND COUNT(H1.plane_name) = (SELECT COUNT(plane_name) FROM Hangar);

/* Division with JOINS */
SELECT SP1.Pilot_name
  FROM (((SELECT plane_name FROM Hangar) AS H1
         INNER JOIN
         (SELECT pilot_name, plane_name FROM PilotSkills) AS SP1
         ON H1.plane_name = SP1.plane_name)
       INNER JOIN (SELECT *
                     FROM PilotSkills
                    WHERE pilot_name = 'Higgins') AS H2
       ON H2.plane_name = H1.plane_name)
       GROUP BY SP1.Pilot_name
HAVING COUNT(*) >= (SELECT COUNT(*)
                      FROM PilotSkills
                     WHERE pilot_name = 'Higgins');