SQL query between three tables

Question

This is a basic extract of the film rental platform I'm working on. To show you, I just need these three tables.

Film

Title        | Genre         |
-------------+---------------+
Why Me       | Romantic      |
The ET       | Fantasy       |
...          | ...           |
Planet       | Documentary   |

User

ID           | Name          |
-------------+---------------+
213          | Jonh D        |
34267        | Smith E       |
...          | ...           |
256          | Sally F       |

Rent

User_ID      | Film_Title    | Date        |
-------------+---------------+-------------+
34267        | The ET        | 2015-11-01  |
256          | Planet        | 2014-12-03  |
...          | ...           | ...         |
256          | Why Me        | 2016-03-04  |

That said, I need to do a SQL query that associates to each Film.Genre the User.Name that have rented the highest amount of films for that genre.

ID           | Genre         |
-------------+---------------+
Sally F      | Romantic      |
Smith E      | Fantasy       |
...          | ...           |
Sally F      | Documentary   |

I would have posted some of my attempts but honestly I didn't come out with anything which is barely sense making. I know that using JOIN statement would be easier that trying to build it with nested statements but I am stumped and this is so frustrating.

SELECT u.Name, f.Genre
FROM User AS u JOIN Rent AS r JOIN Film AS f
GROUP BY f.Genre
ORDER BY(COUNT(r.User_ID))

Answer 1

This is assuming that the genre field is in your rentals table:

select user_id, genre, max(rentals) from
(select 
    user_id,
    genre, 
    count(*) as rentals 
 from rent group by user_id, genre)
 group by user_id, genre;

Answer 2

You could use a subquery like this one:

SELECT sub.Name, sub.Genre, MAX(rent_number)
FROM (
    SELECT User.Name, Film.Genre, Count(User.ID) as rent_number
    FROM Film
      INNER JOIN Rent ON Film.Title = Rent.Film_Title
      INNER JOIN User ON Rent.User_ID = User.ID
    GROUP BY User.Name, Film.Genre) sub 
GROUP BY sub.Genre