CREATE TABLE genres (name VARCHAR2, id VARCHAR2)
CREATE TABLE tracks (genre_id VARCHAR2)

Find number of tracks in each genre?
SELECT COUNT(*), T1.name FROM genres AS T1 JOIN tracks AS T2 ON T1.id = T2.genre_id GROUP BY T1.name
SELECT COUNT(*), "T1"."name" FROM "genres" "T1" JOIN "tracks" "T2" ON "T1"."id" = "T2"."genre_id" GROUP BY "T1"."name"