SQL - Get consecutively minimum numbers - sql

Question

Title may not make sense so I will provide some context.
I have a table, call it Movies.
A movie tuple has the values: Name, Director, Genre, Year
I'm trying to create a query that allows me to return all Directors who have never released two consecutive Horror films with more than 4 years apart.
I'm not sure where I'd begin but I'm trying to start off by creating a query that given some specific year, returns the next minimum year, so that I can check if the difference between these two is less than 4, and keep doing that for all movies.
My attempt was:
SELECT D1.Director
FROM Movies D1
WHERE D1.Director NOT IN
(SELECT D2.Director FROM Director D2
WHERE D2.Director = D1.Director
AND D2.Genre = 'Horror'
AND D1.Genre = 'Horror' AND D2.Year - D1.Year > 4
OR D1.Year - D2.Year > 4)
which does not work for obvious reasons.
I've also had a few attempts using joins, and it works on films that follow a pattern such as 2000, 2003, 2006, but fail if more than 3 films.

Answer 1

You could try this:
Select all data, and use lag or lead to return the last or next year. After that look at the difference between the two.
WITH TempTable AS (
SELECT
Name,
Director,
Genre,
Year,
LAG(Year) OVER (PARTITION BY Name, Director, Genre ORDER BY Year ASC) AS 'PriorYear'
FROM
Movies
WHERE
Genre = 'Horror'
)
SELECT
Name,
Director
FROM
TempTable
GROUP BY
Name,
Director
HAVING
MAX(Year-PriorYear) < 2

Answer 2

Try this:
SELECT * FROM (
SELECT director, min(diff) as diff FROM (
SELECT m1.director, m1.year as year1, m2.year as year2, m2.year-m1.year as diff
FROM `movies` m1, movies m2
WHERE m1.director = m2.director and m1.name <> m2.name and m1.year<=m2.year
and m1.genre='horror' and m2.genre='horror'
) d1 group by director
) d2 WHERE diff>4
First, in the inner Select it will list all movie pairs of directors' horror movies with year difference calculated, then minimum of these are selected (for consecutiveness), then longer than 4 years differences are selected...