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Please start to use join syntax instead of an IN clause:
select a.first_name,
a.actor_id,
fc.film_id,
c.name,
c.category_id
from actor a
left join film_actor fa
on a.actor_id = fa.actor_id
left join film_category fc
fa.film_id = fc.film_id
left join category c
on fc.category_id = ...