XML+LINQ

<?xml version="1.0" encoding="utf-8" ?>
<Data>
  <Products>
    <Product Name="West Side Story" Price="9.99m" SuppelierID="1"/>
    <Product Name="Assassins" Price="14.99m" SuppelierID="2"/>
    <Product Name="Frogs" Price="13.99m" SuppelierID="1"/>
    <Product Name="Sweeney Todd" Price="9.99m" SuppelierID="3"/>
  </Products>
  <Suppliers>
    <Supplier Name="Solely Sondheim" SupplierID="1"/>
    <Supplier Name="CD-by-CD-by-Sondheim" SupplierID="2"/>
    <Supplier Name="Barbershop CDs" SupplierID="3"/>
  </Suppliers>
</Data>

using System.Xml.Linq;

namespace ConsoleApplication1
{
    class XML_LINQ
    {
        static void Main()
        {
            //将产品和供货商连接起来，价格高于10美元，先按供货商名排序，在按产品名排序，最后打印供货商名和产品名
            //供货商和产品编码使用XML文件
            XDocument doc = XDocument.Load("data.xml");    //XDocument使用命名空间System.Xml.Linq;
            var filtered = from p in doc.Descendants("Product")
                            join s in doc.Descendants("Supplier")
                            on (int)p.Attribute("SupplierID")
                            equals (int)s.Attribute("SupplierID")
                            where (decimal)p.Attribute("Price") > 10
                            orderby (string)s.Attribute("Name"), (string)p.Attribute("Name")
                            select new
                            {
                                SupplierName = (string)s.Attribute("Name"),
                                ProductName = (string)s.Attribute("Name")
                            };
            foreach (var v in filtered)
            {
                Console.WriteLine("Supplier={0};Product={1}", v.SupplierName, v.ProductName);
            }
        }
    }
}