What are the names of the directors who made exactly one movie excluding director NULL?
CREATE TABLE reviewer (
    rid number,
    name text
)

CREATE TABLE rating (
    rid number,
    mid number,
    stars number,
    ratingdate time
)

CREATE TABLE movie (
    mid number,
    title text,
    year number,
    director text
)
SELECT director FROM movie WHERE director <> "null" GROUP BY director HAVING COUNT(*) = 1
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What are the names of the directors who made exactly one movie excluding director NULL? ### Input: CREATE TABLE reviewer (
    rid number,
    name text
)

CREATE TABLE rating (
    rid number,
    mid number,
    stars number,
    ratingdate time
)

CREATE TABLE movie (
    mid number,
    title text,
    year number,
    director text
) ### Response: SELECT director FROM movie WHERE director <> "null" GROUP BY director HAVING COUNT(*) = 1