DB.mephi_ada/BD_4s/task_from_lection.sql

INSERT INTO A VALUES
(1,2),
(2,3);

INSERT INTO B VALUES
(1,1),
(2,3);

INSERT INTO C VALUES
(1,2,1,1),
(1,2,2,2),
(2,3,1,1),
(1,2,4,5);


SELECT a.F1, a.F2 FROM a,b,c
WHERE a.F1 = c.F1 AND a.F2 = c.F2 AND b.F3 = c.F3 AND b.F4 = c.F4
GROUP BY a.F1, a.F2 HAVING COUNT (a.F1) = (SELECT COUNT(F3) FROM b);

SELECT F1, F2 FROM C
    WHERE F3 IN (SELECT F3 FROM B) AND F4 IN (SELECT F4 FROM B)
    GROUP BY F1, F2 HAVING COUNT(*) = (
        SELECT COUNT(*) FROM b
    );