I'm trying to answer a specific question "Which film is the most popular in category “Sports”?" 
I've tried this 

```
WITH CustomerRentalsPerStore AS
(
    SELECT  R.customer_id, I.category_id,  COUNT (R.inventory_id) as rental_count 
    from    rental AS R
            INNER JOIN inventory AS I 
                on R.inventory_id = I.inventory_id
    GROUP BY customer_id, I.category_id
    --ORDER BY COUNT (R.inventory_id) desc
)

SELECT c.customer_id, c.first_name, c.last_name, cr.rental_count, cr.store_id 
FROM    Customer C
        INNER JOIN CustomerRentalsPerStore CR
            on  C.customer_id = CR.customer_id
where   cr.rental_count = (SELECT MAX(rental_count) FROM CustomerRentalsPerStore)       
 AND CR.category_id='Sports'

```

Here are the ER Diagrams:

[![Here are the ER Diagrams](https://i.stack.imgur.com/IMKSK.png)](https://i.stack.imgur.com/IMKSK.png)

Any help would be appreciated! Thank you