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 AdventureWorks2008R2;
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>
...