/media/sda-magnetic/david/Dok-15-2023-11-27/informatik/www-intel-compute-stick-2022-06-13/030/databasemenge.txt

a and b
a and c
b and c

a or b
a or c
b or c

(a or b) and c = a and c or b and c
(a or c) and b = a and b or c and b
(b or c) and a = a and b or c and a

SELECT x FROM (SELECT x FROM a INTERSECT SELECT x FROM b)x ORDER BY x;
SELECT x FROM (SELECT x FROM a INTERSECT SELECT x FROM c)x ORDER BY x;
SELECT x FROM (SELECT x FROM b INTERSECT SELECT x FROM c)x ORDER BY x;

SELECT x FROM (SELECT x FROM a UNION SELECT x FROM b)x ORDER BY x;
SELECT x FROM (SELECT x FROM a UNION SELECT x FROM c)x ORDER BY x;
SELECT x FROM (SELECT x FROM b UNION SELECT x FROM c)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM a UNION SELECT x FROM b)x
    INTERSECT
    SELECT x FROM c
)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM a INTERSECT SELECT x FROM c)x
    UNION
    SELECT x FROM (SELECT x FROM b INTERSECT SELECT x FROM c)x
)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM a UNION SELECT x FROM c)x
    INTERSECT
    SELECT x FROM b
)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM a INTERSECT SELECT x FROM b)x
    UNION 
    SELECT x FROM (SELECT x FROM c INTERSECT SELECT x FROm b)x
)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM b UNION SELECT x FROM c)x
    INTERSECT
    SELECT x FROM a
)x ORDER BY x;

SELECT x FROM (
    SELECT x FROM (SELECT x FROM b INTERSECT SELECT x FROM a)x
    UNION
    SELECT x FROM (SELECT x FROM c INTERSECT SELECT x FROM a)x
)x ORDER BY x;