CREATE TABLE song (artist_name VARCHAR2, f_id VARCHAR2)
CREATE TABLE files (f_id VARCHAR2, duration VARCHAR2)

What is the name of the artist who produced the shortest song?
SELECT T1.artist_name FROM song AS T1 JOIN files AS T2 ON T1.f_id = T2.f_id ORDER BY T2.duration LIMIT 1
SELECT "T1"."artist_name" FROM "song" "T1" JOIN "files" "T2" ON "T1"."f_id" = "T2"."f_id" ORDER BY "T2"."duration" FETCH FIRST 1 ROWS ONLY