SELECT SUM(num_of_component) FROM furniture
How many furniture components are there in total?
CREATE TABLE manufacturer (
    manufacturer_id number,
    open_year number,
    name text,
    num_of_factories number,
    num_of_shops number
)

CREATE TABLE furniture_manufacte (
    manufacturer_id number,
    furniture_id number,
    price_in_dollar number
)

CREATE TABLE furniture (
    furniture_id number,
    name text,
    num_of_component number,
    market_rate number
)