CREATE TABLE flight(
	flno number(4,0) primary key,
	origin varchar2(20),
	destination varchar2(20),
	distance number(6,0),
	departure_date date,
	arrival_date date,
	price number(7,2),
    aid number(9,0),
    foreign key("aid") references `aircraft`("aid"))

CREATE TABLE aircraft(
	aid number(9,0) primary key,
	name varchar2(30),
	distance number(6,0))

CREATE TABLE employee(
	eid number(9,0) primary key,
	name varchar2(30),
	salary number(10,2))

CREATE TABLE certificate(
	eid number(9,0),
	aid number(9,0),
	primary key(eid,aid),
	foreign key("eid") references `employee`("eid"),
	foreign key("aid") references `aircraft`("aid"))
SELECT T3.name FROM Employee AS T1 JOIN Certificate AS T2 ON T1.eid  =  T2.eid JOIN Aircraft AS T3 ON T3.aid  =  T2.aid WHERE T1.name  =  "John Williams"
Show names for all aircrafts of which John Williams has certificates.