CREATE TABLE table_name_20 (constructor VARCHAR2, chassis VARCHAR2, driver VARCHAR2)

Who constructed the car that Derek Warwick raced in with a TG181 chassis?
SELECT constructor FROM table_name_20 WHERE chassis = "tg181" AND driver = "derek warwick"
SELECT "constructor" FROM "table_name_20" WHERE "chassis" = "tg181" AND "derek warwick" = "driver"