How many engineers did each staff contact? List both the contact staff name and number of engineers contacted.
create table engineer_visits (contact_staff_id varchar, PRIMARY KEY (contact_staff_id)); create table staff (staff_name varchar, staff_id varchar, PRIMARY KEY (staff_name))
select t1.staff_name, count(*) from staff as t1 join engineer_visits as t2 on t1.staff_id = t2.contact_staff_id group by t1.staff_name