Question: Are there any captains that are included in both lists? | Did you mean ships that are included in both lists? | Oh sorry, yes ships that are included in both lists
SQL: SELECT t1.name FROM ship AS t1 JOIN captain AS t2 ON t1.ship_id   =   t2.ship_id WHERE t2.rank   =   'Midshipman' INTERSECT SELECT t1.name FROM ship AS t1 JOIN captain AS t2 ON t1.ship_id   =   t2.ship_id WHERE t2.rank   =   'Lieutenant'