Question

我是postgres的新手，我无法找到如何查询以下内容的示例：

{
"Skill": {
        "Technical": [
            { "Name": "C#",
              "Rating": 4,
              "Last Used": "2014-08-21"
            },
            { "Name": "ruby",
              "Rating": 4,
              "Last Used": "2014-08-21"
            }

        ],
        "Product": [
            { "Name": "MDM",
              "Rating": 4,
              "Last Used": "2014-08-21"
            },
            { "Name": "UDM",
              "Rating": 5,
              "Last Used": "2014-08-21"
            }
        ]
    }
}

简而言之，我一直在努力理解如何通过地图查询，而不必明确命名每个键。

我有一个查询执行以下操作，但似乎有点太多了...

Select  'Technical' as SkillType
        , json_array_elements(ResourceDocument->'Skill'->'Technical')->>'Name' as SkillName 
        , json_array_elements(ResourceDocument->'Skill'->'Technical')->>'Rating' as Rating
        , json_array_elements(ResourceDocument->'Skill'->'Technical')->>'Last Used' as LastUsed
    FROM testdepot.Resource

    UNION ALL

    Select 'Product' as SkillType
        , json_array_elements(ResourceDocument->'Skill'->'Product')->>'Name' as SkillName   
        , json_array_elements(ResourceDocument->'Skill'->'Product')->>'Rating' as Rating
        , json_array_elements(ResourceDocument->'Skill'->'Product')->>'Last Used' as LastUsed
    FROM testdepot.Resource

我试图在1个查询中找到一种方法来执行此操作，该查询允许包含地图的所有键。在这种情况下产品和技术类似的东西：

Select 'Product' as SkillType
        , json_array_elements(ResourceDocument->'Skill'->*)->>'Name' as SkillName   
        , json_array_elements(ResourceDocument->'Skill'->*)->>'Rating' as Rating
        , json_array_elements(ResourceDocument->'Skill'->*)->>'Last Used' as LastUsed
    FROM testdepot.Resource

Answer 1

您可以在子查询中包含对json_object_keys的调用，以首先获取"Skill"中的键，然后对结果使用外部查询json_array_elements：

SELECT SkillType
, json_array_elements(ResourceDocument->'Skill'->SkillType)->>'Name' AS SkillName 
, json_array_elements(ResourceDocument->'Skill'->SkillType)->>'Rating' AS Rating
, json_array_elements(ResourceDocument->'Skill'->SkillType)->>'Last Used' AS LastUsed
FROM (
    SELECT json_object_keys(resourcedocument->'Skill') AS SkillType, ResourceDocument
    FROM Resource
) t;

带有嵌入式json对象的PostgreSQL JSON查询

1 个答案: