Example: Specify the ID and IDREF directives

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Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

This example is almost the same as the Specifying the ELEMENTXSINIL Directive example. The only difference is that the query specifies the ID and IDREF directives. These directives overwrite the types of the SalesPersonID attribute in the <OrderHeader> and <OrderDetail> elements, and form intra-document links. You need the schema to see the overwritten types. Therefore, the query specifies the XMLDATA option in the FOR XML clause to retrieve the schema.

USE AdventureWorks2022;
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 IN (43659, 43661)

UNION ALL
SELECT 2 as Tag,
       1 as Parent,
        SalesOrderID,
        NULL,
        NULL,
        SalesPersonID,
        NULL,
        NULL,
        NULL,
        NULL
FROM   Sales.SalesOrderHeader
WHERE  SalesOrderID IN (43659, 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;

This is the partial result. In the schema, the ID and IDREF directives have overwritten the data types of the SalesOrderID attribute in the <OrderHeader> and <OrderDetail> elements. If you remove these directives, the schema returns original types of these attributes.

<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>
...

See also