What is the id of the first complaint?
select complaint_id from complaints order by date_complaint_raised asc limit 1
Which staff id was there for it?
select staff_id from complaints order by date_complaint_raised asc limit 1
What was the last name of this staff member?
select t1.last_name from staff as t1 join complaints as t2 on t1.staff_id = t2.staff_id order by t2.date_complaint_raised limit 1