範例：指定 ID 和 IDREF 指示詞

此範例幾乎與＜指定 ELEMENTXSINIL 指示詞＞範例相同。唯一的差異在於查詢會指定 ID 和 IDREF 指示詞。這些指示詞會覆寫 <OrderHeader> 及 <OrderDetail> 元素中的 SalesPersonID 屬性類型。這會形成內部文件連結。您需要結構描述，才能查看遭到覆寫的類型。因此，查詢會在 FOR XML 子句中指定 XMLDATA 選項，以擷取結構描述。

USE AdventureWorks2008R2;
GO
SELECT  1 as Tag,
        0 as Parent,
        SalesOrderID  as [OrderHeader!1!SalesOrderID!id],
        OrderDate     as [OrderHeader!1!OrderDate],
        CustomerID    as [OrderHeader!1!CustomerID],
        NULL          as [SalesPerson!2!SalesPersonID],
        NULL          as [OrderDetail!3!SalesOrderID!idref],
        NULL          as [OrderDetail!3!LineTotal],
        NULL          as [OrderDetail!3!ProductID],
        NULL          as [OrderDetail!3!OrderQty]
FROM   Sales.SalesOrderHeader
WHERE  SalesOrderID=43659 or SalesOrderID=43661
UNION ALL 
SELECT 2 as Tag,
       1 as Parent,
        SalesOrderID, 
        NULL,
        NULL,
        SalesPersonID,  
        NULL,         
        NULL,         
        NULL,
        NULL         
FROM   Sales.SalesOrderHeader
WHERE  SalesOrderID=43659 or SalesOrderID=43661
UNION ALL
SELECT 3 as Tag,
       1 as Parent,
        SOD.SalesOrderID,
        NULL,
        NULL,
        SalesPersonID,
        SOH.SalesOrderID,
        LineTotal,
        ProductID,
        OrderQty   
FROM    Sales.SalesOrderHeader SOH,Sales.SalesOrderDetail SOD
WHERE   SOH.SalesOrderID = SOD.SalesOrderID
AND     (SOH.SalesOrderID=43659 or SOH.SalesOrderID=43661)
ORDER BY [OrderHeader!1!SalesOrderID!id], [SalesPerson!2!SalesPersonID],
         [OrderDetail!3!SalesOrderID!idref],[OrderDetail!3!LineTotal]
FOR XML EXPLICIT, XMLDATA;

以下是部分結果。請注意在結構描述中，ID 和 IDREF 指示詞已覆寫 <OrderHeader> 和 <OrderDetail> 元素中 SalesOrderID 屬性的資料類型。如果您移除這些指示詞，結構描述就會傳回這些屬性的原始類型。

<Schema name="Schema1" xmlns="urn:schemas-microsoft-com:xml-data" xmlns:dt="urn:schemas-microsoft-com:datatypes">

<ElementType name="OrderHeader" content="mixed" model="open">

<AttributeType name="SalesOrderID" dt:type="id" />

<AttributeType name="OrderDate" dt:type="dateTime" />

<AttributeType name="CustomerID" dt:type="i4" />

<attribute type="SalesOrderID" />

<attribute type="OrderDate" />

<attribute type="CustomerID" />

</ElementType>

<ElementType name="SalesPerson" content="mixed" model="open">

<AttributeType name="SalesPersonID" dt:type="i4" />

<attribute type="SalesPersonID" />

</ElementType>

<ElementType name="OrderDetail" content="mixed" model="open">

<AttributeType name="SalesOrderID" dt:type="idref" />

<AttributeType name="LineTotal" dt:type="number" />

<AttributeType name="ProductID" dt:type="i4" />

<AttributeType name="OrderQty" dt:type="i2" />

<attribute type="SalesOrderID" />

<attribute type="LineTotal" />

<attribute type="ProductID" />

<attribute type="OrderQty" />

</ElementType>

</Schema>

<OrderHeader xmlns="x-schema:#Schema1" SalesOrderID="43659" OrderDate="2001-07-01T00:00:00" CustomerID="676">

<SalesPerson SalesPersonID="279" />

<OrderDetail SalesOrderID="43659" LineTotal="10.373000" ProductID="712" OrderQty="2" />

...

</OrderHeader>

...