CREATE TABLE ship (name VARCHAR, ship_id VARCHAR)
CREATE TABLE captain (ship_id VARCHAR, rank VARCHAR)

Find the name of the ships that are steered by both a captain with Midshipman rank and a captain with Lieutenant rank.
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'
SELECT "t1"."name" FROM "ship" AS "t1" JOIN "captain" AS "t2" ON "t1"."ship_id" = "t2"."ship_id" AND "t2"."rank" = 'Midshipman' INTERSECT SELECT "t1"."name" FROM "ship" AS "t1" JOIN "captain" AS "t2" ON "t1"."ship_id" = "t2"."ship_id" AND "t2"."rank" = 'Lieutenant'