Find all players that play on stadium

CREATE FUNCTION udf_stadium_players_count (stadium_name VARCHAR(30))
RETURNS INT
DETERMINISTIC
BEGIN
    RETURN (SELECT count(p.id) AS count
            FROM players AS p
            RIGHT JOIN teams AS t ON t.id = p.team_id
            RIGHT JOIN stadiums AS s ON s.id = t.stadium_id
            WHERE s.name = stadium_name
            GROUP BY s.id);
END;