我有下一个问题。进行此查询：

select apex_web_service.make_rest_request(
     p_url => 'https://something.com/rest/Discount'
     ,p_http_method => 'GET'
     ,p_username => 'username'
     ,p_password => 'password'
    ) as custom
from dual;

返回以下内容：

{"hasMore":false,"items":[{"id":12,"Origin":"ALL","Part":"PO423S","Channel":"RC"},{"id":13,"Origin":"ALL","Part":"LO123D","Channel":"RC"},{"id":14,"Origin":"ALL","Part":"SD765S","Channel":"AP"}]}

我想做一个频道组，看看有多少频道我必须插入到另一个表。
我试着列出：

select d.custom.items
from  (
    select apex_web_service.make_rest_request(
        p_url =>  'https://something.com/rest/Discount'
       ,p_http_method => 'GET'
       ,p_username => 'username'
       ,p_password => 'password'
    ) as custom
    from dual) d;

但我有个错误：

ORA-22806: no es un objeto ni un elemento REF
22806. 00000 -  "not an object or REF"

* Cause:    An attempt was made to extract an attribute from an item that is

           neither an object nor a REF.

* Action:   Use an object type or REF type item and retry the operation.

Error en la línea: 12, columna: 8

我还测试下一个：

create table temp_json (
  json_data blob not null
);
alter table temp_json
  add constraint temp_data_json 
  check ( json_data is json );

insert into temp_json
select apex_web_service.make_rest_request(
     p_url =>  'https://something.com/rest/Discount'
    ,p_http_method => 'GET'
    ,p_username => 'username'
    ,p_password => 'password
    ) as customDiscAplicability
from dual
;

select d.json_data.items
from   temp_json d;

结果是：

ITEMS
-----
(null)

我遵循这个教程：链接
有人能帮我吗？
当做