-- 7.
SELECT cisdod
FROM dodava
WHERE cissou=15
EXCEPT
SELECT cisdod
FROM dodava
WHERE cissou<>15

-- 8.
SELECT cisdod
FROM dodava
EXCEPT
SELECT cisdod
FROM dodava
WHERE cissou=15

SELECT DISTINCT cisdod FROM dodava
WHERE cissou<>15 AND cisdod NOT IN (
SELECT cisdod FROM dodava WHERE cissou=15
)

-- 9.
SELECT cisdod FROM dodava
WHERE cissou=12
INTERSECT
SELECT cisdod FROM dodava
WHERE cissou=13
INTERSECT
SELECT cisdod FROM dodava
WHERE cissou=15


SELECT DISTINCT cisdod FROM Dodava D
WHERE (12) IN (
SELECT cissou FROM dodava E WHERE D.cisdod = E.cisdod
) AND (13) IN (
SELECT cissou FROM dodava E WHERE D.cisdod = E.cisdod
)AND (15) IN (
SELECT cissou FROM dodava E WHERE D.cisdod = E.cisdod
)
--10
SELECT cisdod FROM dodava
EXCEPT
SELECT DISTINCT cisdod FROM (
    SELECT * FROM (
        SELECT cisdod FROM dodava
    ) R1, (
    SELECT cissou FROM dodava) R2
EXCEPT
SELECT * FROM dodava
) R3



SELECT cisdod FROM dodava
EXCEPT
SELECT cisdod
FROM
(
SELECT DISTINCT A.cisdod, B.cissou FROM dodava A CROSS JOIN dodava B
EXCEPT
SELECT cisdod,cissou FROM dodava

) AS X



--11
SELECT mesto FROM dodavatel
WHERE cisdod IN(
SELECT cisdod FROM dodava
WHERE cissou IN (
SELECT cissou FROM soucastka
WHERE barva = 'cervena'
)
)
--12
SELECT AVG(cena) FROM soucastka
--13



INSERT INTO dodava VALUES (3,15)