LINQ Join Query Operator

The Join operator performs an inner join of two sequences based on matching keys extracted from the elements.

public static void JoinSimpleExample()
{
var customers = new List<Customer>() {
new Customer {Key = 1, Name = "Gottshall" },
new Customer {Key = 2, Name = "Valdes" },
new Customer {Key = 3, Name = "Gauwain" },
new Customer {Key = 4, Name = "Deane" },
new Customer {Key = 5, Name = "Zeeman" }
};

var orders = new List<Order>() {
new Order {Key = 1, OrderNumber = "Order 1" },
new Order {Key = 1, OrderNumber = "Order 2" },
new Order {Key = 4, OrderNumber = "Order 3" },
new Order {Key = 4, OrderNumber = "Order 4" },
new Order {Key = 5, OrderNumber = "Order 5" },
};

var q = from c in customers
join o in orders on c.Key equals o.Key
select new {c.Name, o.OrderNumber};

foreach (var i in q) {
Console.WriteLine("Customer: {0} Order Number: {1}",
i.Name.PadRight(11, ' '), i.OrderNumber);
}

Console.ReadLine();
}

public class Customer
{
public int Key;
public string Name;
}

public class Order
{
public int Key;
public string OrderNumber;
}