SELECT company, main_industry FROM company WHERE NOT company_id IN (SELECT company_id FROM station_company)
What are the main industries of the companies without gas stations and what are the companies?
CREATE TABLE company (
    company_id number,
    rank number,
    company text,
    headquarters text,
    main_industry text,
    sales_billion number,
    profits_billion number,
    assets_billion number,
    market_value number
)

CREATE TABLE station_company (
    station_id number,
    company_id number,
    rank_of_the_year number
)

CREATE TABLE gas_station (
    station_id number,
    open_year number,
    location text,
    manager_name text,
    vice_manager_name text,
    representative_name text
)