Sql 统计嵌套类别记录
我的数据库中有以下架构:Sql 统计嵌套类别记录,sql,postgresql,Sql,Postgresql,我的数据库中有以下架构: CREATE TABLE categories ( id bigint NOT NULL, name character varying NOT NULL, ancestry character varying ); CREATE TABLE video_chats ( id bigint NOT NULL, name character varying NOT NULL, category_id bigint NOT
CREATE TABLE categories (
id bigint NOT NULL,
name character varying NOT NULL,
ancestry character varying
);
CREATE TABLE video_chats (
id bigint NOT NULL,
name character varying NOT NULL,
category_id bigint NOT NULL
);
我有一些视频聊天的嵌套类别:
INSERT INTO categories (id, name, ancestry)
VALUES (1, 'Test category', null);
INSERT INTO categories (id, name, ancestry)
VALUES (2, 'Test category subcategory', '1');
INSERT INTO categories (id, name, ancestry)
VALUES (3, 'Test category subcategory', '1/2');
INSERT INTO video_chats (id, name, category_id)
VALUES (1, 'Test Video 1', '2');
INSERT INTO video_chats (id, name, category_id)
VALUES (2, 'Test Video 2', '3');
现在,我想使用sql查询来统计类别及其子类别的视频聊天。它应该返回以下结果:
- 测试类别-2视频聊天
- 测试类别子类别-1视频聊天
- 测试类别子类别子类别-1视频聊天
t=# with a as (select v.id,unnest(array_append(string_to_array(ancestry,'/')::bigint[],c.id)) cg from video_chats v join categories c on v.category_id = c.id)
select cg,count(1) from a group by cg order by cg;
cg | count
----+-------
1 | 2
2 | 2
3 | 1
(3 rows)
我的结果与预期不同:
统计类别及其子类别的视频聊天次数
因此视频聊天id 1属于类别2,因此(因为2是1到1的子类别,所以它是vc1类别:2,1
视频聊天2属于类别3,因此属于类别2,因此属于类别1,因此vc2类别:3,2,1
在我的查询中,它是CTE主体:
t=# select v.id,array_append(string_to_array(ancestry,'/')::bigint[],c.id) from video_chats v join categories c on v.category_id = c.id; id | array_append
----+--------------
1 | {1,2}
2 | {1,2,3}
(2 rows)
从而导致:
- 测试类别(1)-2视频聊天
- 测试类别子类别(1)-2视频聊天
- 测试类别子类别子类别(3)-1视频聊天
1/2/7
等等。也许您还可以提供可读的预期查询结果。它应该返回行,其中每个行都有两列:category\u id
,video\u chats\u count
@VaoTsun