Mapping Relations Specified for Nested Elements
A schema can include an msdata:Relationship annotation to explicitly specify the mapping between any two elements in the schema. The two elements specified in msdata:Relationship can be nested in the schema, but do not have to be. The mapping process uses msdata:Relationship in the schema to generate the primary key/foreign key relationship between the two columns.
The following example shows an XML Schema in which the OrderDetail element is a child element of Order. The msdata:Relationship identifies this parent-child relationship and specifies that the OrderNumber column of the resulting Order table is related to the OrderNo column of the resulting OrderDetail table.
<xs:schema id="MyDataSet"
xmlns:xs="https://www.w3.org/2001/XMLSchema"
xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
<xs:element name="MyDataSet" msdata:IsDataSet="true">
<xs:complexType>
<xs:choice maxOccurs="unbounded">
<xs:element name="Order">
<xs:complexType>
<xs:sequence>
<xs:element name="OrderNumber" type="xs:string" />
<xs:element name="EmpNumber" type="xs:string" />
<xs:element name="OrderDetail">
<xs:annotation>
<xs:appinfo>
<msdata:Relationship name="OrdODRelation"
msdata:parent="Order"
msdata:child="OrderDetail"
msdata:parentkey="OrderNumber"
msdata:childkey="OrderNo"/>
</xs:appinfo>
</xs:annotation>
<xs:complexType>
<xs:sequence>
<xs:element name="OrderNo" type="xs:string" />
<xs:element name="ItemNo" type="xs:string" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
</xs:element>
</xs:schema>
The XML Schema mapping process creates the following in the DataSet:
An Order and an OrderDetail table.
Order(OrderNumber, EmpNumber) OrderDetail(OrderNo, ItemNo)A relationship between the Order and OrderDetail tables. The Nested property for this relationship is set to True because the Order and OrderDetail elements are nested in the schema.
ParentTable: Order ParentColumns: OrderNumber ChildTable: OrderDetail ChildColumns: OrderNo RelationName: OrdODRelation Nested: True
The mapping process does not create any constraints.
See Also
Concepts
Generating DataSet Relations from XML Schema (XSD)