你如何在数组数组上使用OPENJSON

Question

我有一个JSON结构,其中有Sections,由多个Renders组成,包含多个Fields.

如何在最低级别(字段)上执行1次OPENJSON调用以从中获取所有信息？

这是一个JSON示例:

Declare @layout NVARCHAR(MAX) = N'
    {
        "Sections": [
            {
                "SectionName":"Section1",
                "SectionOrder":1,
                "Renders":[
                    {
                        "RenderName":"Render1",
                        "RenderOrder":1,
                        "Fields":[
                            {
                                "FieldName":"Field1",
                                "FieldData":"Data1"
                            },
                            {
                                "FieldName":"Field2",
                                "FieldData":"Data2"
                            }
                        ]
                    },
                    {
                        "RenderName":"Render2",
                        "RenderOrder":2,
                        "Fields":[
                            {
                                "FieldName":"Field1",
                                "FieldData":"Data1"
                            },
                            {
                                "FieldName":"Field2",
                                "FieldData":"Data2"
                            }
                        ]
                    } 
                ]
            },
            {
                "SectionName":"Section2",
                "SectionOrder":2,
                "Renders":[
                    {
                        "RenderName":"Render1",
                        "RenderOrder":1,
                        "Fields":[
                            {
                                "FieldName":"Field1",
                                "FieldData":"Data1"
                            }
                        ]
                    },
                    {
                        "RenderName":"Render2",
                        "RenderOrder":2,
                        "Fields":[
                            {
                                "FieldName":"Field1",
                                "FieldData":"Data1"
                            },
                            {
                                "FieldName":"Field2",
                                "FieldData":"Data2"
                            }
                        ]
                    } 
                ]
            }
        ]
    }
'

下面是嵌套OPENJSON调用代码的一些示例,它可以工作,但是非常复杂且无法动态生成,如何进行一级调用？

SELECT SectionName, SectionOrder, RenderName, RenderOrder, FieldName, FieldData FROM (
    SELECT SectionName, SectionOrder, RenderName, RenderOrder, Fields FROM (
        select SectionName, SectionOrder, Renders
        from OPENJSON(@layout,'$.Sections') 
        WITH (
            SectionName nvarchar(MAX) '$.SectionName',  
            SectionOrder nvarchar(MAX) '$.SectionOrder', 
            Renders nvarchar(MAX) '$.Renders' as JSON
        )
    ) as Sections
    CROSS APPLY OPENJSON(Renders,'$')
    WITH (
        RenderName nvarchar(MAX) '$.RenderName',  
        RenderOrder nvarchar(MAX) '$.RenderOrder', 
        Fields nvarchar(MAX) '$.Fields' as JSON
    )
) as Renders
CROSS APPLY OPENJSON(Fields,'$')
WITH (
    FieldName nvarchar(MAX) '$.FieldName',  
    FieldData nvarchar(MAX) '$.FieldData'
)

这就是我想要实现的目标:

select FieldName, FieldData
from OPENJSON(@layout,'$.Sections.Renders.Fields') 
WITH (
    FieldName nvarchar(MAX) '$.Sections.Renders.Fields.FieldName',  
    FieldData nvarchar(MAX) '$.Sections.Renders.Fields.FieldData'
)

Answer 1

这可以通过 CROSS 将 JSON 子节点与父节点一起应用并使用 JSON_Value() 函数来完成，如下所示：

 DECLARE @json NVARCHAR(1000)   
    SELECT @json =    
    N'{   
      "OrderHeader": [  
        {   
          "OrderID": 100,  
          "CustomerID": 2000,   
          "OrderDetail": [   
            {  
              "ProductID": 2000,   
              "UnitPrice": 350      
            },      
            {             
              "ProductID": 3000,   
              "UnitPrice": 450  
            },   
            {               
              "ProductID": 4000,  
              "UnitPrice": 550   
            }   
          ]   
        }    
      ]   
    }'   
        
    SELECT   
        JSON_Value (c.value, '$.OrderID') as OrderID,    
        JSON_Value (c.value, '$.CustomerID') as CustomerID,    
        JSON_Value (p.value, '$.ProductID') as ProductID,    
        JSON_Value (p.value, '$.UnitPrice') as UnitPrice   
         
    FROM OPENJSON (@json, '$.OrderHeader') as c   
    CROSS APPLY OPENJSON (c.value, '$.OrderDetail') as p   
    
    Result 
    -------
    OrderID CustomerID  ProductID   UnitPrice
    100     2000        2000        350
    100     2000        3000        450
    100     2000        4000        550

Answer 2

虽然无法仅使用单个OPENJSON，但可以通过删除嵌套的子查询来简化查询，使其更易于动态创建：

SELECT SectionName, SectionOrder, RenderName, RenderOrder, FieldName, FieldData
FROM OPENJSON(@layout, '$.Sections') 
WITH (
    SectionName NVARCHAR(MAX) '$.SectionName',  
    SectionOrder NVARCHAR(MAX) '$.SectionOrder', 
    Renders NVARCHAR(MAX) '$.Renders' AS JSON
)
CROSS APPLY OPENJSON(Renders,'$')
WITH (
    RenderName NVARCHAR(MAX) '$.RenderName',  
    RenderOrder NVARCHAR(MAX) '$.RenderOrder', 
    Fields NVARCHAR(MAX) '$.Fields' AS JSON
)
CROSS APPLY OPENJSON(Fields,'$')
WITH (
    FieldName NVARCHAR(MAX) '$.FieldName',  
    FieldData NVARCHAR(MAX) '$.FieldData'
)