列名为 XPath 节点测试的列
适用于： 
SQL Server Azure SQL 数据库 Azure SQL 托管实例
如果列名是某个 XPath 节点测试，将如下表所示映射该列的内容。 如果列名是某个 XPath 节点测试，则该列的内容将映射到相应的节点。 如果该列的 SQL 类型是 xml，将返回一个错误。
| 列名称 | 行为 |
|---|---|
| text() | 对于名为 text() 的列，该列中的字符串值将被添加为文本节点。 |
| comment() | 对于名为 comment() 的列，该列中的字符串值将被添加为 XML 注释。 |
| node() | 对于列名为 node() 的列，结果与列名为通配符 (*) 时相同。 |
| 处理指令（名称） | 如果列名为处理指令，该列中的字符串值将被添加为此处理指令目标名称的 PI 值。 |
以下查询显示用作列名的节点测试。 它在得到的 XML 中添加文本节点和注释。
USE AdventureWorks2022;
GO
SELECT E.BusinessEntityID "@EmpID",
'Example of using node tests such as text(), comment(), processing-instruction()' as "comment()",
'Some PI' as "processing-instruction(PI)",
'Employee name and address data' as "text()",
'middle name is optional' as "EmpName/text()",
FirstName as "EmpName/First",
MiddleName as "EmpName/Middle",
LastName as "EmpName/Last",
AddressLine1 as "Address/AddrLine1",
AddressLine2 as "Address/AddrLIne2",
City as "Address/City"
FROM HumanResources.Employee AS E
INNER JOIN Person.Person AS P
ON P.BusinessEntityID = E.BusinessEntityID
INNER JOIN Person.BusinessEntityAddress AS BAE
ON BAE.BusinessEntityID = E.BusinessEntityID
INNER JOIN Person.Address AS A
ON BAE.AddressID = A.AddressID
WHERE E.BusinessEntityID=1
FOR XML PATH;
结果如下：
<row EmpID="1">
<!--Example of using node tests such as text(), comment(), processing-instruction() -->
<?PI Some PI?>
Employee name and address data
<EmpName>middle name is optional
<First>Ken</First>
<Last>Sánchez</Last>
</EmpName>
<Address>
<AddrLine1>4350 Minute Dr.</AddrLine1>
<City>Minneapolis</City>
</Address>
</row>