What is the description of the service type which offers both the photo product and the film product?
create table ref_service_types (service_type_description varchar, service_type_code varchar, PRIMARY KEY (service_type_description)); create table services (service_type_code varchar, product_name varchar, PRIMARY KEY (service_type_code))
select t1.service_type_description from ref_service_types as t1 join services as t2 on t1.service_type_code = t2.service_type_code where t2.product_name = 'photo' intersect select t1.service_type_description from ref_service_types as t1 join services as t2 on t1.service_type_code = t2.service_type_code where t2.product_name = 'film'