列名为 XPath 节点测试的列

适用于：SQL ServerAzure 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	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>

另请参阅

• 将 PATH 模式与 FOR XML 一起使用