mysql count group by having
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 relationship. I want a query to find the total number of movies which have at exactly 4 genres. The current query I have is
SELECT COUNT(*)
FROM Movies
GROUP BY ID
HAVING COUNT(Genre) = 4
However, this returns me a list of 4's instead of the total sum. How do I get the sum total sum instead of a list of count(*)
?
Solution 1:
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.
Solution 2:
SELECT COUNT(*)
FROM (SELECT COUNT(*)
FROM movies
GROUP BY id
HAVING COUNT(genre) = 4) t