使用 T-SQL 进行动态 JSON 解析

Question

我有一个高度非结构化的 JSON 字符串，作为调用 REST API 的响应：

{
    "info": "Test Json Structure",
    "Owner": "Self-Owned",
    "managedObjects": [{
            "Name": "Device1",
            "Class": "A"
        }, {
            "Name": "Device2",
            "Class_145": "Ax01",
            "Class_11": "B",
            "Type_125478": {
                "Model": "1",
                "Manufacturer": "External"
            },
            "Type_SD": {
                "Model": "00",
                "Manufacturer": "Internal"
                }
        }, {
            "Name": "Device3",
            "Class_x": "Cx11",
            "Class_T": "C8Y",
            "Type": {
                "Model": "1x",
                "Manufacturer": "Internal"
            }
        }
    ]
}

如何使用 T-SQL 动态解析这个对象，让所有子元素代表一个表的列？更重要的是，如何处理Type、Type_125478、Type_SD 对象，实际上它们具有相同的结构（Model, Manufacturer），但它们的名称有些不同。另请注意，设备可能会发送一个新的标识符 (Type_XYZ)，它以前不存在，但幸运的是具有相同的结构 (Model, Manufacturer)。

Answer 1

您可以使用类似的方法将全部分解为表格结构并继续执行此操作（需要 SQL-Server v2016+ 版本）：

DECLARE @YourJSON NVARCHAR(MAX)=
N'{
    "info": "Test Json Structure",
    "Owner": "Self-Owned",
    "managedObjects": [{
            "Name": "Device1",
            "Class": "A"
        }, {
            "Name": "Device2",
            "Class_145": "Ax01",
            "Class_11": "B",
            "Type_125478": {
                "Model": "1",
                "Manufacturer": "External"
            },
            "Type_SD": {
                "Model": "00",
                "Manufacturer": "Internal"
                }
        }, {
            "Name": "Device3",
            "Class_x": "Cx11",
            "Class_T": "C8Y",
            "Type": {
                "Model": "1x",
                "Manufacturer": "Internal"
            }
        }
    ]
}';

--查询

SELECT A.info
      ,A.[Owner]
      ,C.[key] AS TagName
      ,CASE WHEN D.Model IS NULL THEN C.[value] END AS TagValue 
      ,D.Model
      ,D.Manufacturer
FROM OPENJSON(@YourJSON)
WITH(info NVARCHAR(MAX)
    ,[Owner] NVARCHAR(MAX)
    ,managedObjects NVARCHAR(MAX) AS JSON) A
OUTER APPLY OPENJSON(A.managedObjects) B
OUTER APPLY OPENJSON(B.[value]) C
OUTER APPLY OPENJSON(CASE WHEN ISJSON(C.[value])=1 THEN C.[value] END) 
WITH (Model NVARCHAR(MAX)
     ,Manufacturer NVARCHAR(MAX))D;

--结果

+---------------------+------------+-------------+----------+-------+--------------+
| info                | Owner      | TagName     | TagValue | Model | Manufacturer |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Name        | Device1  |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Class       | A        |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Name        | Device2  |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Class_145   | Ax01     |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Class_11    | B        |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Type_125478 |          | 1     | External     |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Type_SD     |          | 00    | Internal     |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Name        | Device3  |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Class_x     | Cx11     |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Class_T     | C8Y      |       |              |
+---------------------+------------+-------------+----------+-------+--------------+
| Test Json Structure | Self-Owned | Type        |          | 1x    | Internal     |
+---------------------+------------+-------------+----------+-------+--------------+

提示：您可以将B.[key] 作为对象标识符添加到结果中。

简单的想法

• 我们使用第一个 OPENJSON 进入您的 JSON。 WITH-clause 允许将 JSON-props 寻址为列。我们将 managedObejcts 作为自己的 JSON 返回。
• 我们再使用一个OPENJSON 来深入了解托管对象。
• 这将返回一个对象数组。我们可以将value 传递给另一个OPENJSON。
• 只要 value 可以单独解释为 JSON，我们就再使用一个 OPENJSON，这次再次使用 WITH 子句来获取内部道具作为列。

您可以将此结果插入到表中（声明的、临时的、物理的...）并继续使用此易于阅读的集。