Question

我有一个postgresql表，它有一个json格式的列。

示例列值：

{"Apple":{"category":"fruit","price":100},"Orange":{"category":"fruit","price":80}}

现在我想选择此列，并为每行中的所有项目提取"price"。

查询获取列：

select items from my_table

要提取特定项目的json值，我可以使用

select items -> 'Orange' -> 'price' as price
from my_table

但是如何提取所有商品（Apple，Orange）的价格？作为阵列可能。

Answer 1

使用json_each()，例如：

with my_table(items) as (
    values (
    '{"Apple":{"category":"fruit","price":100},"Orange":{"category":"fruit","price":80}}'::json
    )
)

select key, (value->>'price')::numeric as price
from my_table,
json_each(items)

  key   | price 
--------+-------
 Apple  |   100
 Orange |    80
(2 rows)

Answer 2

t=# with my_table(items) as (
  values('{"Apple":{"category":"fruit","price":100},"Orange":{"category":"fruit","price":80}}'::json)
)
select
  json_object_keys(items)
, items->json_object_keys(items)->>'price'
from my_table;
 json_object_keys | ?column?
------------------+----------
 Apple            | 100
 Orange           | 80
(2 rows)

json_object_keys： https://www.postgresql.org/docs/9.5/static/functions-json.html

从sql表中的json中提取所有值

2 个答案: