Joe Celko’s page examples

DROP TABLE IF EXISTS PilotSkills; CREATE TABLE PilotSkills (pilot_name CHAR(15) NOT NULL, plane_name CHAR(15) NOT NULL, PRIMARY KEY (pilot_name, plane_name)); DROP TABLE IF EXISTS Hangar; CREATE TABLE Hangar (plane_name CHAR(15) NOT NULL PRIMARY KEY); INSERT INTO PilotSkills VALUES ('Celko', 'Piper Cub'); INSERT INTO PilotSkills VALUES ('Higgins', 'B-52 Bomber'); INSERT INTO PilotSkills VALUES ('Higgins', 'F-14 Fighter'); INSERT INTO PilotSkills VALUES ('Higgins', 'Piper Cub'); INSERT INTO PilotSkills VALUES ('Jones', 'B-52 Bomber'); INSERT INTO PilotSkills VALUES ('Jones', 'F-14 Fighter'); INSERT INTO PilotSkills VALUES ('Smith', 'B-1 Bomber'); INSERT INTO PilotSkills VALUES ('Smith', 'B-52 Bomber'); INSERT INTO PilotSkills VALUES ('Smith', 'F-14 Fighter'); INSERT INTO PilotSkills VALUES ('Wilson', 'B-1 Bomber'); INSERT INTO PilotSkills VALUES ('Wilson', 'B-52 Bomber'); INSERT INTO PilotSkills VALUES ('Wilson', 'F-14 Fighter'); INSERT INTO PilotSkills VALUES ('Wilson', 'F-17 Fighter'); INSERT INTO Hangar VALUES ('B-1 Bomber'); INSERT INTO Hangar VALUES ('B-52 Bomber'); INSERT INTO Hangar VALUES ('F-14 Fighter');

-- A method made popular by C. Date in his textbooks 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)));

Exact division as proposed by Celko

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);

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