CREATE TABLE Aircraft (name VARCHAR, aid VARCHAR)
CREATE TABLE Certificate (eid VARCHAR, aid VARCHAR)
CREATE TABLE Employee (eid VARCHAR, name VARCHAR)

Show names for all aircrafts of which John Williams has certificates.
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"
SELECT "T3"."name" FROM "Employee" AS "T1" JOIN "Certificate" AS "T2" ON "T1"."eid" = "T2"."eid" JOIN "Aircraft" AS "T3" ON "T2"."aid" = "T3"."aid" WHERE "John Williams" = "T1"."name"