根据数据库值限制返回的结果

如何解决根据数据库值限制返回的结果

我有两个表格，类别和故事。

Stories 表包含按类别组织的内容。

categories_id,category_name,category_story_count
1,news,2
2,funnies,3

stories_id,categories_id,story_name,story_content,story_active
1,1,"Tax Hike","blah blah",1
2,"Tax Cuts","Election",1 
4,2,"Peanuts",1
5,"Garfield",1
6,"Archie",1 

我想要一个查询，该查询将根据 category_story_count 返回每个类别的正确故事数量，以及故事是否处于活动状态 (story_active = 1)

所以结果应该是这样的：

"news","Tax Hike"
"news","Tax Cuts"
"funnies","Peanuts"
"funnies","Garfield"
"funnies","Archie"

两个“新闻”故事，因为新闻类别 1 的 category_story_count = 2，三个“搞笑”故事，因为搞笑 2 的 category_story_count = 3

我已经尝试过内部连接、嵌套和限制，但就是无法让它返回我想要的东西。

任何帮助将不胜感激。

编辑： MysqL 版本（） 8.0.23

解决方法

这是使用窗口函数的解决方案：

with cte as ( 
  select *,row_number() over (partition by c.categories_id order by s.stories_id) as rownum 
  from Categories as c join Stories as s using (categories_id) 
) select * from cte where rownum <= category_story_count;

+---------------+---------------+----------------------+------------+------------+---------------+--------------+--------+
| categories_id | category_name | category_story_count | stories_id | story_name | story_content | story_active | rownum |
+---------------+---------------+----------------------+------------+------------+---------------+--------------+--------+
|             1 | new           |                    2 |          1 | Tax Hike   | blah blah     |            1 |      1 |
|             1 | new           |                    2 |          2 | Tax Cuts   | blah blah     |            1 |      2 |
|             2 | funnies       |                    3 |          4 | Peanuts    | blah blah     |            1 |      1 |
|             2 | funnies       |                    3 |          5 | Garfield   | blah blah     |            1 |      2 |
|             2 | funnies       |                    3 |          6 | Archie     | blah blah     |            1 |      3 |
+---------------+---------------+----------------------+------------+------------+---------------+--------------+--------+

在 MySQL 8.0.23 上测试。