Linq查询加入两个对象并计算总和

Question

我有两个对象列表,我需要加入Sku,然后caluclate Sum(Qty*Price).我不确定该怎么做？这是我到目前为止:

List<Order> orders = new List <Order> 
{ 
    new Order() { Sku = "ABC", Qty = 1 },
    new Order() { Sku = "XYZ", Qty = 2}
};

List<Cost> costs = new List <Cost> 
{ 
    new Cost() { Sku = "ABC", Price = 4.50m },
    new Cost() { Sku = "XYZ", Price = 2.25m }
};


var profit = from order in orders
             join cost in costs
             on order.Sku equals cost.Sku
             select Sum(order.Qty * cost.Price)

Answer 1

更改您的最后一部分如下:

var profit = (from order in orders
             join cost in costs
             on order.Sku equals cost.Sku
             select (order.Qty * cost.Price)).Sum();

取自这里:Stackoverflow问题,回答如何总结