#region Types
public enum Countries
{
USA,
Italy,
}
public class Customer
{
public string Name {get;set;}
public string City { get; set; }
public Countries Country { get; set; }
public Order[] Orders { get; set; }
public override string ToString()
{
return String.Format("Name: {0} - City: {1} - Country: {2}",
this.Name, this.City, this.Country);
}
}
public class Order
{
public int IdOrder { get; set; }
public int Quantity { get; set; }
public bool Shipped { get; set; }
public string Month { get; set; }
public int IdProduct { get; set; }
public override string ToString()
{
return String.Format("IdOrder: {0} - IdProduct: {1} - Quantity: {2} - Shipped: {3} - Month: {4}",
this.IdOrder, this.IdProduct, this.Quantity, this.Shipped, this.Month);
}
}
public class Product
{
public int IdProduct { get; set; }
public decimal Price { get; set; }
public override string ToString()
{
return String.Format("IdProduct: {0} - Price: {1}", this.IdProduct, this.Price);
}
}
#endregion
class Program
{
private static Customer[] customers;
private static Product[] products;
static void LoadData()
{
customers = new Customer[] {
new Customer {Name = "Paolo", City = "Brescia", Country = Countries.Italy, Orders = new Order[] {
new Order {IdOrder = 1, Quantity = 3, IdProduct = 1, Shipped = false, Month = "January"},
new Order {IdOrder = 2, Quantity = 5, IdProduct = 2, Shipped = true, Month = "May"}}},
new Customer {Name = "Marco", City = "Torino", Country = Countries.Italy, Orders = new Order[] {
new Order {IdOrder = 3, Quantity = 10, IdProduct = 1, Shipped = false, Month = "July"},
new Order {IdOrder = 4, Quantity = 20, IdProduct = 3, Shipped = true, Month = "December"}}},
new Customer {Name = "James", City = "Dallas", Country = Countries.USA, Orders = new Order[] {
new Order {IdOrder = 5, Quantity = 20, IdProduct = 3, Shipped = true, Month = "December"}}},
new Customer {Name = "Frank", City = "Seattle", Country = Countries.USA, Orders = new Order[] {
new Order {IdOrder = 6, Quantity = 20, IdProduct = 5, Shipped = false, Month = "July"}}}};
products = new Product[] {
new Product {IdProduct = 1, Price = 10 },
new Product {IdProduct = 2, Price = 20 },
new Product {IdProduct = 3, Price = 30 },
new Product {IdProduct = 4, Price = 40 },
new Product {IdProduct = 5, Price = 50 },
new Product {IdProduct = 6, Price = 60 }};
}
static Program()
{
LoadData();
}
static void Main(string[] args)
{
// restrictionOperatorWithIndex();
// projectionWithIndex();
//selectManySample();
selectManySampleWithCustomSelector();
}
//使用分页的Where
static void restrictionOperatorWithIndex()
{
var expr = customers
.Where((c, index) => (c.Country == Countries.Italy && index >= 1))
.Select(c => new { c.Name });
foreach (var item in expr)
{
Console.WriteLine(item);
}
}
//使用分页的Select
static void projectionWithIndex()
{
var expr =
customers
.Select((c, index) => new { index, c.Name, c.Country });
foreach (var item in expr)
{
Console.WriteLine(item);
}
}
//SelectMany
static void selectManySample()
{
var orders = customers
.Where(c => c.Country == Countries.Italy)
.SelectMany(c =>c.Orders);
//查询表达式
//var orders = from c in customers
// where c.Country == Countries.Italy
// from o in c.Orders
// select o;
foreach (var item in orders)
{
Console.WriteLine(item);
}
}
static void selectManySampleWithCustomSelector()
{
var items = customers
.Where(c => c.Country == Countries.Italy)
.SelectMany(c => c.Orders, (c, o) => new { o.Quantity, o.IdProduct });
//查询表达式
//var items = from c in customers
// where c.Country == Countries.Italy
// from o in c.Orders
// select new { o.Quantity, o.IdProduct };
foreach (var item in items)
{
Console.WriteLine(item);
}
}
}
