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annotation-interpretation-sql-relationship-and-key-ordering-rule.md

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title description author ms.author ms.date ms.service ms.subservice ms.topic monikerRange
sql:relationship and the Key Ordering Rule (SQLXML)
Learn about using the sql:relationship element and key ordering rules in SQLXML.
MikeRayMSFT
mikeray
03/17/2017
sql
xml
reference
=azuresqldb-current||>=sql-server-2016||>=sql-server-linux-2017||=azuresqldb-mi-current

Annotation Interpretation - sql:relationship and Key Ordering Rule

[!INCLUDE SQL Server Azure SQL Database] Because XML Bulk Load generates records as their nodes enter into scope and sends those records to Microsoft [!INCLUDEssNoVersion] as their nodes exit scope, the data for the record must be present within the scope of the node.

Consider the following XSD schema, in which the one-to-many relationship between <Customer> and <Order> elements (one customer can place many orders) is specified by using the <sql:relationship> element:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"<>   
            xmlns:sql="urn:schemas-microsoft-com:mapping-schema">  
<xsd:annotation>  
  <xsd:appinfo>  
    <sql:relationship name="CustCustOrder"  
          parent="Cust"  
          parent-key="CustomerID"  
          child="CustOrder"  
          child-key="CustomerID" />  
  </xsd:appinfo>  
</xsd:annotation>  
  
  <xsd:element name="Customers" sql:relation="Cust" >  
   <xsd:complexType>  
     <xsd:sequence>  
       <xsd:element name="CustomerID"  type="xsd:integer" />  
       <xsd:element name="CompanyName" type="xsd:string" />  
       <xsd:element name="City"        type="xsd:string" />  
       <xsd:element name="Order"   
                          sql:relation="CustOrder"  
                          sql:relationship="CustCustOrder" >  
         <xsd:complexType>  
          <xsd:attribute name="OrderID" type="xsd:integer" />  
         </xsd:complexType>  
       </xsd:element>  
     </xsd:sequence>  
    </xsd:complexType>  
  </xsd:element>  
</xsd:schema>

As the <Customer> element node enters into scope, XML Bulk Load generates a customer record. This record stays until XML Bulk Load reads </Customer>. In processing the <Order> element node, XML Bulk Load uses <sql:relationship> to obtain the value of the CustomerID foreign key column of the CustOrder table from the <Customer> parent element, because the <Order> element does not specify the CustomerID attribute. This means that in defining the <Customer> element, you must specify the CustomerID attribute in the schema before you specify <sql:relationship>. Otherwise, when an <Order> element enters into scope, XML Bulk Load generates a record for the CustOrder table, and when the XML Bulk Load reaches the </Order> end tag, it sends the record to [!INCLUDEssNoVersion] without the CustomerID foreign key column value.

Save the schema that is provided in this example as SampleSchema.xml.

To test a working sample

  1. Create these tables:

    CREATE TABLE Cust (  
              CustomerID     int          PRIMARY KEY,  
           CompanyName    varchar(20)  NOT NULL,  
              City           varchar(20)  DEFAULT 'Seattle')  
GO  
CREATE TABLE CustOrder (  
              OrderID        varchar(10) PRIMARY KEY,  
           CustomerID     int         FOREIGN KEY REFERENCES                                          Cust(CustomerID))  
GO

  2. Save the following sample data as SampleXMLData.xml:

    <ROOT>    
  <Customers>  
    <CompanyName>Hanari Carnes</CompanyName>  
    <City>NY</City>  
    <Order OrderID="1" />  
    <Order OrderID="2" />  
    <CustomerID>1111</CustomerID>  
  </Customers>  
  <Customers>  
    <CompanyName>Toms Spezialitten</CompanyName>  
     <City>LA</City>    
    <Order OrderID="3" />  
    <CustomerID>1112</CustomerID>  
  </Customers>  
  <Customers>  
    <CompanyName>Victuailles en stock</CompanyName>  
    <Order OrderID="4" />  
    <CustomerID>1113</CustomerID>  
  </Customers>  
</ROOT>

  3. To execute XML Bulk Load, save and execute the following [!INCLUDEmsCoName] Visual Basic Scripting Edition (VBScript) example as MySample.vbs:

    set objBL = CreateObject("SQLXMLBulkLoad.SQLXMLBulkload.4.0")  
objBL.ConnectionString = "provider=SQLOLEDB;data source=localhost;database=tempdb;integrated security=SSPI"  
objBL.ErrorLogFile = "c:\error.log"  
objBL.CheckConstraints = True  
objBL.Transaction=True  
objBL.Execute "c:\SampleSchema.xml", "c:\SampleXMLData.xml"  
set objBL=Nothing

    The result is that XML Bulk Load inserts a NULL value in the CustomerID foreign key column of the CustOrder table. If you revise the XML sample data so that the <CustomerID> child element appears before the <Order> child element, you get the expected result: XML Bulk Load inserts the specified foreign key value into the column.

This is the equivalent XDR schema:

<?xml version="1.0" ?>  
<Schema xmlns="urn:schemas-microsoft-com:xml-data"   
        xmlns:dt="urn:schemas-microsoft-com:xml:datatypes"    
        xmlns:sql="urn:schemas-microsoft-com:xml-sql" >   
   <ElementType name="CustomerID"  />  
   <ElementType name="CompanyName" />  
   <ElementType name="City"        />  
  
   <ElementType name="root" sql:is-constant="1">  
      <element type="Customers" />  
   </ElementType>  
  
   <ElementType name="Customers" sql:relation="Cust" >  
      <element type="CustomerID" sql:field="CustomerID" />  
      <element type="CompanyName" sql:field="CompanyName" />  
      <element type="City" sql:field="City" />  
      <element type="Order" >  
                 <sql:relationship  
                        key-relation    ="Cust"  
                        key             ="CustomerID"  
                        foreign-key     ="CustomerID"  
                        foreign-relation="CustOrder" />  
      </element>  
   </ElementType>  
    <ElementType name="Order" sql:relation="CustOrder" >  
      <AttributeType name="OrderID" />  
      <AttributeType name="CustomerID" />  
      <attribute type="OrderID" />  
      <attribute type="CustomerID" />  
    </ElementType>  
</Schema>