SELECT name ,  CLASS FROM ship WHERE ship_id NOT IN (SELECT ship_id FROM captain)
what are the names and classes of the ships that do not have any captain yet?
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 )
what are the names and classes of the ships that do not have any captain yet ?