What are the product ids for the problems reported by Christop Berge with closure authorised by Ashley Medhurst?
create table problems (reported_by_staff_id varchar, closure_authorised_by_staff_id varchar, PRIMARY KEY (reported_by_staff_id)); create table staff (staff_id varchar, staff_first_name varchar, staff_last_name varchar, PRIMARY KEY (staff_id))
select product_id from problems as t1 join staff as t2 on t1.reported_by_staff_id = t2.staff_id where t2.staff_first_name = "christop" and t2.staff_last_name = "berge" intersect select product_id from problems as t1 join staff as t2 on t1.closure_authorised_by_staff_id = t2.staff_id where t2.staff_first_name = "ashley" and t2.staff_last_name = "medhurst"