SELECT director FROM Movie WHERE director != "null" GROUP BY director HAVING count(*)  =  1
What are the names of the directors who made exactly one movie excluding director NULL?
SELECT director FROM Movie WHERE director ! = `` null '' GROUP BY director HAVING count ( * ) = 1
select director from movie where director ! = value group by director having count ( * ) = value
What are the names of the directors who made exactly one movie excluding director NULL ?