JSON数据库表查询答案

【问题标题】：JSON database table queryJSON数据库表查询
【发布时间】：2021-04-07 17:27:59
【问题描述】：

我有一些对象的 JSON 表，我正在尝试查询对象中的金额值

{
"authorizations": [
{
  "id": "d50",
  "type": "passed",
  "amount": 100,
  "fortId": 5050,
  "status": "GENERATED",
  "voided": false,
  "cardNumber": 3973,
  "expireDate": null,
  "description": "Success",
  "customerCode": "858585",
  "paymentMethod": "cash",
  "changeDatetime": null,
  "createDatetime": 000000000,
  "reservationCode": "202020DD",
  "authorizationCode": "D8787"
},
{
  "id": "d50",
  "type": "passed",
  "amount": 100,
  "fortId": 5050,
  "status": "GENERATED",
  "voided": false,
  "cardNumber": 3973,
  "expireDate": null,
  "description": "Success",
  "customerCode": "858585",
  "paymentMethod": "cash",
  "changeDatetime": null,
  "createDatetime": 000000000,
  "reservationCode": "202020DD",
  "authorizationCode": "D8787"
 }
 ],
 }

我尝试了以下四个选项，但这些选项都没有给我对象的值：

SELECT info @> 'authorizations:[{amount}]'
FROM idv.reservations;

SELECT info -> 'authorizations:[{amount}]'
FROM idv.reservations;

info -> ''authorizations' ->> 'amount'
FROM idv.reservations

select (json_array_elements(info->'authorizations')->'amount')::int from idv.reservations

注意我正在使用 DBeaver

【问题讨论】：

标签： sql arrays json postgresql lateral-join

【解决方案1】：

如果您希望“授权”JSON 数组中包含的每个对象有一行，并具有相应的数量，您可以使用横向连接和jsonb_array_elements()：

select r.*, (x.obj ->> 'amount')::int as amount
from reservations r
cross join lateral jsonb_array_elements(r.info -> 'authorizations') x(obj)

我们还可以一次提取所有金额并将它们放入一个数组中，如下所示：

select r.*, 
    jsonb_path_query_array(r.info, '$.authorizations[*].amount') as amounts
from reservations r

Demo on DB Fiddlde

【讨论】：