Return the names and classes of ships that do not have a captain?
SELECT name ,  CLASS FROM ship WHERE ship_id NOT IN (SELECT ship_id FROM captain)
SELECT name ,  CLASS FROM ship WHERE ship_id NOT IN (SELECT ship_id FROM captain)
[{'Name': 'HMS Trojan', 'Class': 'KR'}, {'Name': 'HM Sloop Sparrow', 'Class': 'KR'}, {'Name': 'HMS Phalarope', 'Class': 'KR'}, {'Name': 'HMS Undine', 'Class': 'GL'}]