示例：指定 ELEMENTXSINIL 指令

当指定 ELEMENT 指令检索以元素为中心的 XML 时，如果列具有 NULL 值，则 EXPLICIT 模式将不生成相应的元素。 另外，也可以指定 ELEMENTXSINIL 指令以请求为 xsi:nil 属性设置为 TRUE 值的 NULL 值生成元素。

以下查询构造包括雇员地址的 XML。 对于 AddressLine2 和 City 列，列名指定 ELEMENTXSINIL 指令。 这将为行集中的 AddressLine2 和 City 列中的 NULL 值生成元素。

USE AdventureWorks2012;  
GO  
SELECT 1    as Tag,  
       NULL as Parent,  
       E.BusinessEntityID  as [Employee!1!EmpID],  
       BEA.AddressID as [Employee!1!AddressID],  
       NULL        as [Address!2!AddressID],  
       NULL        as [Address!2!AddressLine1!ELEMENT],  
       NULL        as [Address!2!AddressLine2!ELEMENTXSINIL],  
       NULL        as [Address!2!City!ELEMENTXSINIL]  
FROM   HumanResources.Employee AS E  
INNER JOIN Person.BusinessEntityAddress AS BEA  
    ON E.BusinessEntityID = BEA.BusinessEntityID  
  
UNION ALL  
SELECT 2 as Tag,  
       1 as Parent,  
       E.BusinessEntityID,  
       BEA.AddressID,  
       A.AddressID,  
       AddressLine1,   
       AddressLine2,  
       City   
FROM   HumanResources.Employee AS E  
INNER JOIN Person.BusinessEntityAddress AS BEA  
    ON E.BusinessEntityID = BEA.BusinessEntityID  
INNER JOIN Person.Address AS A  
    ON BEA.AddressID = A.AddressID  
ORDER BY [Employee!1!EmpID],[Address!2!AddressID]  
FOR XML EXPLICIT;  

下面是部分结果：

<Employee xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

EmpID="1" AddressID="249">

<Address AddressID="249">

<AddressLine1>4350 Minute Dr.</AddressLine1>

<AddressLine2 xsi:nil="true" />

<City>Minneapolis</City>

</Address>

</Employee>

...

另请参阅

将 EXPLICIT 模式与 FOR XML 一起使用