Which engineer has visited the most times? Show 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 GROUP BY T1.engineer_id ORDER BY count(*) DESC LIMIT 1
engineer who has visited the most times refers to MAX(COUNT(visit_id)); showing engineer id, first name, and last name requires selecting engineer_id, first_name, last_name;