mysql count group by having

Question

I have this table:

Movies (ID, Genre)

A movie can have multiple genres, so an ID is not specific to a genre, it is a many to many relations

Answer 1

SELECT COUNT(*) 
FROM   (SELECT COUNT(*) 
        FROM   movies 
        GROUP  BY id 
        HAVING COUNT(genre) = 4) t

Answer 2

Maybe

SELECT count(*) FROM (
    SELECT COUNT(*) FROM Movies GROUP BY ID HAVING count(Genre) = 4
) AS the_count_total

although that would not be the sum of all the movies, just how many have 4 genre's.

So maybe you want

SELECT sum(
    SELECT COUNT(*) FROM Movies GROUP BY ID having Count(Genre) = 4
) as the_sum_total

Answer 3

One way would be to use a nested query:

SELECT count(*)
FROM (
   SELECT COUNT(Genre) AS count
   FROM movies
   GROUP BY ID
   HAVING (count = 4)
) AS x

The inner query gets all the movies that have exactly 4 genres, then outer query counts how many rows the inner query returned.

Answer 4

What about:

SELECT COUNT(*) FROM (SELECT ID FROM Movies GROUP BY ID HAVING COUNT(Genre)=4) a