Câu 16 Phần III

-- Cau 16:
SELECT HOTEN
FROM GIAOVIEN
WHERE MAGV =
        (
            SELECT MAGV
            FROM GIANGDAY GD1
            WHERE MAMH = 'CTRR' AND EXISTS
                    (
                        SELECT *
                        FROM GIANGDAY GD2
                        WHERE GD1.HOCKY = GD2.HOCKY AND GD1.NAM = GD2.NAM
                    )
            GROUP BY MAGV, HOCKY
            HAVING COUNT(MALOP) >= 2
        )