data.xml

<?xml version="1.0" encoding="utf-8" ?>
<Data>
  <Products>
    <Product Name="West Side Story" Price="9.99" SupplierID="1" />
    <Product Name="Assassins" Price="14.99" SupplierID="2" />  
    <Product Name="Frogs" Price="13.99" SupplierID="1" />
    <Product Name="Sweeney Todd" Price="10.99" SupplierID="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>

通过 linq to xml ，查找价格超过10的产品，并打印供应商名称与产品名称；

            XDocument doc = XDocument.Load("data.xml");
            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
                           select new
                           {
                               ProductName = (string)p.Attribute("Name"),
                               SupplierName = (string)s.Attribute("Name")
                           };

            foreach (var v in filtered)
            {
                Console.WriteLine("SupplierName={0} , ProductName={1}", v.SupplierName, v.ProductName);
            }

输出

SupplierName=CD-by-CD-by-Sondheim , ProductName=Assassins
SupplierName=Solely Sondheim , ProductName=Frogs
SupplierName=Barbershop CDs , ProductName=Sweeney Todd

 

参考资料

1、深入理解C#(第2版)；