Among those engineers who have visited, which engineer makes the least number of visits? List the engineer id, first name and last name.
SELECT T1.engineer_id ,  T1.first_name ,  T1.last_name 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(*) ASC LIMIT 1
least number of visits refers to MIN(count(visit)); listing engineer id, first name, and last name involves selecting engineer_id, first_name, last_name; those who have visited implies a join between Maintenance_Engineers and Engineer_Visits tables on engineer_id;