如何获取JSONB数组索引

Question

我确定对此有一个简单的答案，但我就是找不到。我需要获取 JSON 数组元素作为行，但它们的索引与后续处理有关。这是一个[非常简化]的例子：

id  content                                                 
--  ------------------------------------------------------------------
80  {"id":"107-80", "Sections": [{"parts":5},{"parts":8},{"parts":4}]}

我需要得到：

id section section_content 
-- ------- --------------- 
80 0       {"parts":5}     
80 1       {"parts":8}     
80 2       {"parts":4}

我试过：

select
  id,
  row_number() over() - 1 as section, 
  jsonb_array_elements(content -> 'Sections') as section_content
from purchase

但是section列计算不正确，如下图：

id  section  section_content 
--- -------- --------------- 
80  0        {"parts":5}     
80  0        {"parts":8}     
80  0        {"parts":4}

Answer 1

您可以使用with ordinality

select p.id, s.*
from purchase p
  cross join jsonb_array_elements(p.content -> 'Sections') with ordinality as s(section_content, section)

Answer 2

您可以将其用作 CTE

CREATE TABLE purchase (
  "id" INTEGER,
  "content" JSONB
);

INSERT INTO purchase
  ("id", "content")
VALUES
  ('80', '{"id":"107-80", "Sections": [{"parts":5},{"parts":8},{"parts":4}]}');

WITH CTE AS (select
  id,
  jsonb_array_elements(content -> 'Sections') as section_content
from purchase)
SELECT
id,  ROW_NUMBER () OVER (
      PARTITION BY id)  as section, section_content FROM CTE

id | section | section_content
-: | ------: | :--------------
80 |       1 | {"parts": 5}   
80 |       2 | {"parts": 8}   
80 |       3 | {"parts": 4}

db<>fiddle here

如何获取JSONB数组索引

How to get JSONB array index

sql

postgresql

json

jsonb