sql-server - 如何在使用“xml 路径”从 SQL Server 2008 生成 xml 文件时仅将 xsi:nil="true" 添加到一个字段

Question

这是我正在使用的代码：

DECLARE @returnXML XML  

SELECT   @ReturnXML = 
(SELECT [StudentID/SSN] = ssn, 
        [StudentName/LastName] = lastname,
        [StudentName/FirstName] = firstname,
        [StudentName/MiddleInitial] = Middlename,
        [PrimaryAddress/Street1] = line1,
        [PrimaryAddress/Street2] = line2,
        [PrimaryAddress/City] = city,
        [PrimaryAddress/State] = state,
        [PrimaryAddress/Country] = ISNULL(country,null),
        [PrimaryAddress/Zip] = zipcode

FROM StudentTable
FOR     XML Path('Student'), ROOT('Root'),TYPE
)

SELECT  @ReturnXML  
FOR     XML PATH('');

只有国家节点才需要设置 xsi:nil="true"。谢谢

Answer 1

使用 XSINIL 参数为 NULL 值生成元素

添加ELEMENTS XSINIL到FOR XML子句中。

SELECT   @ReturnXML = 
(SELECT [StudentID/SSN] = ssn, 
        [StudentName/LastName] = lastname,
        [StudentName/FirstName] = firstname,
        [StudentName/MiddleInitial] = Middlename,
        [PrimaryAddress/Street1] = line1,
        [PrimaryAddress/Street2] = line2,
        [PrimaryAddress/City] = city,
        [PrimaryAddress/State] = state,
        [PrimaryAddress/Country] = country,
        [PrimaryAddress/Zip] = zipcode
FROM StudentTable
FOR XML Path('Student'), ROOT('Root'), TYPE, ELEMENTS XSINIL
)

以上将为xsi:nil="true"XML 中的所有节点设置NULL.

要仅对一个字段执行此操作，您可以使用子查询ELEMENTS XSINIL来为该字段构建 XML。

SELECT   @ReturnXML = 
(SELECT [StudentID/SSN] = ssn, 
        [StudentName/LastName] = lastname,
        [StudentName/FirstName] = firstname,
        [StudentName/MiddleInitial] = Middlename,
        [PrimaryAddress/Street1] = line1,
        [PrimaryAddress/Street2] = line2,
        [PrimaryAddress/City] = city,
        [PrimaryAddress/State] = state,
        [PrimaryAddress] = (SELECT Country = country FOR XML PATH(''), TYPE, ELEMENTS XSINIL),
        [PrimaryAddress/Zip] = zipcode
FROM StudentTable
FOR XML Path('Student'), ROOT('Root'), TYPE
)