CREATE TABLE program (program_id NUMBER, name CLOB, origin CLOB, launch NUMBER, owner CLOB)
CREATE TABLE broadcast_share (channel_id NUMBER, program_id NUMBER, date CLOB, share_in_percent NUMBER)
CREATE TABLE broadcast (channel_id NUMBER, program_id NUMBER, time_of_day CLOB)
CREATE TABLE channel (channel_id NUMBER, name CLOB, owner CLOB, share_in_percent NUMBER, rating_in_percent NUMBER)

find the number of different programs that are broadcast during night time.
SELECT COUNT(DISTINCT program_id) FROM broadcast WHERE time_of_day = 'Night'
SELECT COUNT(DISTINCT "program_id") FROM "broadcast" WHERE "time_of_day" = 'Night'