在AWS Redshift中查询不同的JSON字符串

Is there a way in AWS Redshift to query all key/value pairs from a JSON string where each record has a different number of key/value pairs?

AWS Redshift中是否有一种方法可以从JSON字符串中查询所有键/值对，其中每个记录具有不同数量的键/值对？

I.e. in the below example, the first animal has the 'location' attribute whereas the second does not. Using the json_extract_path_text function I can pick out attributes I know exist for both records but when trying to query the location it will fail:

即在下面的例子中，第一只动物具有“位置”属性而第二只动物没有。使用json_extract_path_text函数，我可以选择我知道存在的两个记录的属性，但在尝试查询位置时，它将失败：

   create table test.jsondata(json varchar(65000));
    insert into  test.jsondata(json) values ('{ "animal_id": 1, "name": "harry", "animal_type": "cat", "age": 2, "location": "oakland"}');
    insert into  test.jsondata(json) values ('{ "animal_id": 2, "name": "louie","animal_type": "dog", "age": 4}');

    select 
      json_extract_path_text(JSON,'animal_id') animal_id,
      json_extract_path_text(JSON,'name') name,
      json_extract_path_text(JSON,'animal_type') animal_type,
      json_extract_path_text(JSON,'age') age,
      json_extract_path_text(JSON,'location') location
    from test.jsondata
    order by animal_id;

ERROR: 42601: syntax error at or near "location"

错误：42601：“位置”或附近的语法错误

Desired Outcome:

期望的结果：

animal_id name animal_type age location
1 harry cat 2 oakland
2 louie dog 4 NULL

1 个解决方案

#1

Found that that json_extract_path_text works with ISNULL:

发现json_extract_path_text与ISNULL一起使用：

select 
      json_extract_path_text(JSON,'animal_id') animal_id,
      json_extract_path_text(JSON,'name') name,
      json_extract_path_text(JSON,'animal_type') animal_type,
      json_extract_path_text(JSON,'age') age,
      ISNULL(json_extract_path_text(JSON,'location'),NULL) location
    from test.jsondata
    order by animal_id;