CREATE TABLE artist (artist_name CLOB, country CLOB, gender CLOB, preferred_genre CLOB)
CREATE TABLE song (song_name CLOB, artist_name CLOB, country CLOB, f_id NUMBER, genre_is CLOB, rating NUMBER, languages CLOB, releasedate TIME, resolution NUMBER)
CREATE TABLE genre (g_name CLOB, rating CLOB, most_popular_in CLOB)
CREATE TABLE files (f_id NUMBER, artist_name CLOB, file_size CLOB, duration CLOB, formats CLOB)

What is the average duration of songs that have mp3 format and resolution below 800?
SELECT AVG(T1.duration) FROM files AS T1 JOIN song AS T2 ON T1.f_id = T2.f_id WHERE T1.formats = "mp3" AND T2.resolution < 800
SELECT AVG("T1"."duration") FROM "files" "T1" JOIN "song" "T2" ON "T1"."f_id" = "T2"."f_id" AND "T2"."resolution" < 800 WHERE "T1"."formats" = "mp3"