с условиями if if else в mysql

Question

Я хочу найти все категории фильмов, в которых есть от 55 до 65 фильмов. Вернуть названия этих категорий и количество фильмов в категории, отсортированных по количеству фильмов. Если между 55 и 65 нет категорий, верните наибольшее из доступных значений.

SELECT 
    c.name,
    fc.category_id,
    COUNT(fc.category_id) as ccc
FROM
    film_category fc
JOIN category as c on
    c.category_id = fc.category_id
GROUP BY
    fc.category_id
HAVING CASE 
    WHEN ccc BETWEEN 55 AND 65 THEN ccc
    WHEN ccc NOT BETWEEN 55 AND 65 THEN ccc LIMIT 3 //or we can get only the largest one
  --ELSE ccc NOT BETWEEN 55 AND 65  // or we can do it with else?
END
ORDER BY
    ccc DESC;

, как это сделать наилучшим образом?

конечно, результат моего запроса не совсем верно, потому что я получаю все строки, даже не между 55 и 65

, и это мой результат без ограничения 3

+-------------+-------------+-----+
| name        | category_id | ccc |
+-------------+-------------+-----+
| Sports      |          15 |  74 |
| Foreign     |           9 |  73 |
| Family      |           8 |  69 |
| Documentary |           6 |  68 |
| Animation   |           2 |  66 |
| Action      |           1 |  64 |
| New         |          13 |  63 |
| Drama       |           7 |  62 |
| Sci-Fi      |          14 |  61 |
| Games       |          10 |  61 |
| Children    |           3 |  60 |
| Comedy      |           5 |  58 |
| Classics    |           4 |  57 |
| Travel      |          16 |  57 |
| Horror      |          11 |  56 |
| Music       |          12 |  51 |
+-------------+-------------+-----+
16 rows in set (0.01 sec)

пример данных таблицы категорий:

mysql> select * from category;
+-------------+-------------+---------------------+
| category_id | name        | last_update         |
+-------------+-------------+---------------------+
|           1 | Action      | 2006-02-15 04:46:27 |
|           2 | Animation   | 2006-02-15 04:46:27 |
|           3 | Children    | 2006-02-15 04:46:27 |
|           4 | Classics    | 2006-02-15 04:46:27 |
|           5 | Comedy      | 2006-02-15 04:46:27 |
|           6 | Documentary | 2006-02-15 04:46:27 |
|           7 | Drama       | 2006-02-15 04:46:27 |
|           8 | Family      | 2006-02-15 04:46:27 |
|           9 | Foreign     | 2006-02-15 04:46:27 |
|          10 | Games       | 2006-02-15 04:46:27 |
|          11 | Horror      | 2006-02-15 04:46:27 |
|          12 | Music       | 2006-02-15 04:46:27 |
|          13 | New         | 2006-02-15 04:46:27 |
|          14 | Sci-Fi      | 2006-02-15 04:46:27 |
|          15 | Sports      | 2006-02-15 04:46:27 |
|          16 | Travel      | 2006-02-15 04:46:27 |
+-------------+-------------+---------------------+
16 rows in set (0.00 sec)

пример данных таблицы film_category:

mysql> select * from  film_category limit 10;
+---------+-------------+---------------------+
| film_id | category_id | last_update         |
+---------+-------------+---------------------+
|       1 |           6 | 2006-02-15 05:07:09 |
|       2 |          11 | 2006-02-15 05:07:09 |
|       3 |           6 | 2006-02-15 05:07:09 |
|       4 |          11 | 2006-02-15 05:07:09 |
|       5 |           8 | 2006-02-15 05:07:09 |
|       6 |           9 | 2006-02-15 05:07:09 |
|       7 |           5 | 2006-02-15 05:07:09 |
|       8 |          11 | 2006-02-15 05:07:09 |
|       9 |          11 | 2006-02-15 05:07:09 |
|      10 |          15 | 2006-02-15 05:07:09 |
+---------+-------------+---------------------+
10 rows in set (0.01 sec)

Answer 1

Решение для MySQL 8 +

WITH 
cte1 AS ( SELECT c.name,
                 fc.category_id,
                 COUNT(fc.category_id) as cnt
          FROM film_category fc
          JOIN category c ON c.category_id = fc.category_id
          GROUP BY fc.category_id ),
cte2 AS ( SELECT name, 
                 category_id,
                 cnt
          FROM cte1
          WHERE cnt BETWEEN @from AND @to
          ORDER BY cnt DESC )
SELECT name, 
       category_id,
       cnt
FROM cte2
UNION ALL
( SELECT name, 
         category_id,
         cnt
  FROM cte1
  WHERE ( SELECT COUNT(*)
          FROM cte2 ) = 0
  ORDER BY cnt DESC LIMIT 3 )
ORDER BY cnt DESC;

mysql> SET @from := 60;
Query OK, 0 rows affected (0.00 sec)

mysql> SET @to := 65;
Query OK, 0 rows affected (0.00 sec)

mysql> /* query skipped */
+----------+-------------+-----+
| name     | category_id | cnt |
+----------+-------------+-----+
| Action   |           1 |  64 |
| New      |          13 |  63 |
| Drama    |           7 |  62 |
| Games    |          10 |  61 |
| Sci-Fi   |          14 |  61 |
| Children |           3 |  60 |
+----------+-------------+-----+
6 rows in set (0.00 sec)

mysql> SET @from := 35;
Query OK, 0 rows affected (0.00 sec)

mysql> SET @to := 45;
Query OK, 0 rows affected (0.00 sec)

mysql> /* query skipped */
+---------+-------------+-----+
| name    | category_id | cnt |
+---------+-------------+-----+
| Sports  |          15 |  74 |
| Foreign |           9 |  73 |
| Family  |           8 |  69 |
+---------+-------------+-----+
3 rows in set (0.00 sec)

В версии 5+ вы, конечно, можете конвертировать CTE в подзапросы.

Answer 2

Я не пробовал этот запрос, но думаю, что это может быть что-то вроде этого, и это поможет вам продвинуть ваш запрос:

SELECT 
    c.name,
    fc.category_id,
    COUNT(fc.category_id) as ccc
FROM
    film_category fc
INNER JOIN category as c on
    c.category_id = fc.category_id
GROUP BY
    fc.category_id
HAVING ccc > 55 AND ccc < 65