CREATE TABLE host (host_id DECIMAL, name TEXT, nationality TEXT, age TEXT)
CREATE TABLE party_host (party_id DECIMAL, host_id DECIMAL, is_main_in_charge others)
CREATE TABLE party (party_id DECIMAL, party_theme TEXT, location TEXT, first_year TEXT, last_year TEXT, number_of_hosts DECIMAL)

List the themes of parties in ascending order of number of hosts.
SELECT party_theme FROM party ORDER BY number_of_hosts
SELECT "party_theme" FROM "party" ORDER BY "number_of_hosts" NULLS FIRST