SELECT
    partno,
    count(manufacturer)
FROM
    components
WHERE
    partno IN (SELECT partno FROM productions
               WHERE
                    year = 2005
                AND attr is NULL
              )
GROUP BY partno
UNION
SELECT
    partno,
    count(manufacturer)
FROM components
WHERE
    partno IN (SELECT partno FROM productions
               WHERE
                   year = 2005
               AND attr is NULL
              )
GROUP BY partno
)
AND (
        partno NOT IN (SELECT partno FROM components
    )
);

select partno, count(manufacturer)
from components
where partno in
(
   select partno from productions where year=2005 and attr is NULL
)
group by partno

UNION

select partno, count(manufacturer)
from components
where partno in
(
    select partno from productions where year=2005 and attr is NULL
)
AND partno not in (select partno from components)
group by partno;