SQL select query need task

Question

I have two tables city and house (foreign key to house), I need get result true if city's all houses has property has_door = true.

Answer 1

Something like this:

select c.name, min(has_door) as all_houses_in_city_have_doors
from city c 
join house h on h.city_id = c.id
group by c.id, c.name