Challenge: Sequels in SQL

CREATE TABLE movies (id INTEGER PRIMARY KEY AUTOINCREMENT,
    title TEXT,
    released INTEGER,
    sequel_id INTEGER);

INSERT INTO movies 
    VALUES (1, "Harry Potter and the Philosopher's Stone", 2001, 2);
INSERT INTO movies 
    VALUES (2, "Harry Potter and the Chamber of Secrets", 2002, 3);
INSERT INTO movies 
    VALUES (3, "Harry Potter and the Prisoner of Azkaban", 2004, 4);
INSERT INTO movies 
    VALUES (4, "Harry Potter and the Goblet of Fire", 2005, 5);
INSERT INTO movies 
    VALUES (5, "Harry Potter and the Order of the Phoenix ", 2007, 6);
INSERT INTO movies 
    VALUES (6, "Harry Potter and the Half-Blood Prince", 2009, 7);
INSERT INTO movies 
    VALUES (7, "Harry Potter and the Deathly Hallows – Part 1", 2010, 8);
INSERT INTO movies 
    VALUES (8, "Harry Potter and the Deathly Hallows – Part 2", 2011, NULL);


SELECT movies.title AS "movie_title", sequel.title AS "sequel_title"
    FROM movies
    LEFT OUTER JOIN movies sequel
    ON sequel.id = movies.sequel_id;