You should join productioncompanies
to productioncompanymap
.
The table movies
is not needed because the details of the movies are irrelevant:
SELECT COUNT(*)
FROM productioncompanymap m NATURAL JOIN productioncompanies c
WHERE c.production_company_name = 'Pixar Animation Studios';
or, with an INNER
join:
SELECT COUNT(*)
FROM productioncompanymap m INNER JOIN productioncompanies c
ON c.production_company_id = m.production_company_id
WHERE c.production_company_name = 'Pixar Animation Studios';
or, with a correlated subquery:
SELECT COUNT(*)
FROM productioncompanymap
WHERE production_company_id = (
SELECT production_company_id
FROM productioncompanies
WHERE production_company_name = 'Pixar Animation Studios'
);