linq中join用法

public static IEnumerable<TResult> Join<TOuter, TInner, TKey, TResult>( 
    this IEnumerable<TOuter> outer, 
    IEnumerable<TInner> inner, 
    Func<TOuter, TKey> outerKeySelector, 
    Func<TInner, TKey> innerKeySelector, 
    Func<TOuter, TInner, TResult> resultSelector)

		

    class Customer 
    ...{ 
        public int CustomerId ...{ get; set; } 
        public string Name ...{ get; set; } 
        public int Age ...{ get; set; } 
    } 
    class Product 
    ...{ 
        public int ProductId ...{ get; set; } 
        public string Name ...{ get; set; } 
        public string Origin ...{ get; set; } 
    } 
    class Order 
    ...{ 
        public int OrderId ...{ get; set; } 
        public int CustomerId ...{ get; set; } 
        public List<Product> Products ...{ get; set; } 
    } 
    static List<Customer> customers; 
    static List<Product> products; 
    static List<Order> orders; 
    public static void CreateEntities() 
    ...{ 
        customers = new List<Customer>...{ 
            new Customer()...{ CustomerId = 1, Name = "CA", Age=13}, 
            new Customer()...{ CustomerId = 2, Name = "CB", Age=13}, 
            new Customer()...{ CustomerId = 3, Name = "CC", Age=13}, 
            new Customer()...{ CustomerId = 4, Name = "CD", Age=13} 
        }; 
        products = new List<Product>...{ 
            new Product()...{ ProductId = 1, Name = "PA", Origin="P1" }, 
            new Product()...{ ProductId = 2, Name = "PB", Origin="P2" }, 
            new Product()...{ ProductId = 3, Name = "PC", Origin="P1" }, 
            new Product()...{ ProductId = 4, Name = "PD", Origin="P3" } 
        }; 
        orders = new List<Order>...{ 
            new Order()...{ OrderId = 1 , CustomerId =1, 
                Products = new List<Product>...{ 
                    new Product()...{ ProductId = 2, Name = "PB", Origin="P2" }, 
                    new Product()...{ ProductId = 3, Name = "PC", Origin="P1" } 
            }}, 
            new Order()...{ OrderId = 2 , CustomerId =1, 
                Products = new List<Product>...{ 
                    new Product()...{ ProductId = 3, Name = "PC", Origin="P1" }, 
                    new Product()...{ ProductId = 4, Name = "PD", Origin="P3" } 
            }}, 
            new Order()...{ OrderId = 3 , CustomerId =3, 
                Products = new List<Product>...{ 
                    new Product()...{ ProductId = 4, Name = "PD", Origin="P3" } 
            }}, 
            new Order()...{ OrderId = 4 , CustomerId =2, 
                Products = new List<Product>
  
标签：linq linq join