深入探讨SQL Server 2000对XML的支持

 

　　四、XPath查询 架构和模板

　　XPath查询也可以被内嵌进一个XML模板文件中，下面的代码是一个包含XPath查询的
简单的XML模板文件。

<Northwind xmlns:sql="urn:schemas-microsoft-com:xml-sql">
<sql:xpath-query mapping-schema="file4.xdr">
/Customer[@CustomerID='ALFKI']/Order
</sql:xpath-query>
</Northwind>

　　这个查询使用了一个架构(schema）返回CustomerID号为ALFKI的用户的所有的订单，
假如想要使XPath语句运行，必须使用一个XDR架构文件映射不同的XML元素和属性到相
应的数据库表和字段名。下面给出了这个架构文件。

<?xml version="1.0" ?>
<Schema xmlns="urn:schemas-microsoft-com:xml-data"
xmlns:dt="urn:schemas-microsoft-com:datatypes"
xmlns:sql="urn:schemas-microsoft-com:xml-sql">

<ElementType name="Customer" sql:relation="Customers">
<AttributeType name="CustomerID" dt:type="id" />
<AttributeType name="CompanyName" />
<AttributeType name="ContactName" />
<AttributeType name="City" />
<AttributeType name="Fax" />
<AttributeType name="Orders" dt:type=
"idrefs" sql:id-prefix="Ord-" />

<attribute type="CustomerID" />
<attribute type="CompanyName" />
<attribute type="ContactName" />
<attribute type="City" />
<attribute type="Fax" />
<attribute type="Orders" sql:relation=
"Orders" sql:field="OrderID">
<sql:relationship
key-relation="Customers"
key="CustomerID"
foreign-relation="Orders"
foreign-key="CustomerID" />
</attribute>

<element type="Order">
<sql:relationship
key-relation="Customers"
key="CustomerID"
foreign-relation="Orders"
foreign-key="CustomerID" />
</element>
</ElementType>

<ElementType name="Order" sql:relation="Orders">
<AttributeType name="OrderID" dt:type=
"id" sql:id-prefix="Ord-" />
<AttributeType name="EmployeeID" />
<AttributeType name="OrderDate" />
<AttributeType name="RequiredDate" />
<AttributeType name="ShippedDate" />

<attribute type="OrderID" />
<attribute type="EmployeeID" />
<attribute type="OrderDate" />
<attribute type="RequiredDate" />
<attribute type="ShippedDate" />

<element type="OrderDetail">
<sql:relationship
key-relation="Orders"
key="OrderID"
foreign-relation="[Order Details]"
foreign-key="OrderID" />
</element>
<element type="Employee">
<sql:relationship
key-relation="Orders"
key="EmployeeID"
foreign-relation="Employees"
foreign-key="EmployeeID" />
</element>
</ElementType>

<ElementType name="OrderDetail" sql:relation=
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