how many visits did each engineer have?
select count ( * ) ,t1.engineer_id from maintenance_engineers as t1 join engineer_visits as t2 on t1.engineer_id = t2.engineer_id group by t1.engineer_id
can you list the engineer id, first name, and last name of the engineer who had the least number of visits?
select t1.engineer_id, t1.first_name, t1.last_name ,count ( * ) from maintenance_engineers as t1 join engineer_visits as t2 on t1.engineer_id = t2.engineer_id group by t1.engineer_id order by count ( * ) limit 1