Question

我想根据数量加入2个实体的结果。这就是我所拥有的......

订单＃1

OrderID    CustomerID    ItemID    Description    POS#    Cost    Quantity
1          1             1         Apples         111     1.25    3
1          1             2         Oranges        222     1.12    5
1          1             3         Bananas        333     1.17    5

订单＃2

OrderID    CustomerID    ItemID    Description    POS#    Cost    Quantity
2          1             1         Apples         111     1.25    7
2          1             2         Oranges        222     1.12    2
2          1             3         Bananas        333     1.17    5

以下是我用来获取每张票的代码：

public OrderEntity getOrder(int orderId)
{
    var data = from c in Orders
               where c.OrderID == orderId
               select c;
    return data;
}

如何编写LINQ代码以合并2张票，以便获得数量的总和？看起来应该是这样......

订购门票＃1和＃2

CustomerID    ItemID    Description    POS#    Cost    Quantity
1             1         Apples         111     1.25    10
1             2         Oranges        222     1.12    7
1             3         Bananas        333     1.17    10

似乎我应该能够做到这样......

public List<OrderEntity> getCustomerOrders(int customerId)
{
    var data = from c in Orders
               where c.CustomerID == customerId
               select c;
    return data.ToList();
}

问题是我无法弄清楚分组。有很多关于如何编写EF代码进行分组的信息，但是我不确定我是应该在CustomerID上还是在Quantity上进行分组。任何有关如何进行分组的提示都将非常感激。

Answer 1

您应该按CustomerID和ItemID分组：

尝试这样的事情：

public List<OrderEntity> getCustomerOrders(int customerId)
{
    var data = from c in Orders
               where c.CustomerID == customerId
               group c by new { c.CustomerID, c.ItemID } into g
               select new OrderEntity () {
                  CustomerID = g.Key.CustomerID,
                  ItemID =  g.Key.ItemID,
                  Quantity = g.Sum(x => x.Quantity) 
               };
    return data.ToList();
}

我不确定您如何定义数据，但如果您需要在结果中使用Description POS，Cost，请尝试：

public List<OrderEntity> getCustomerOrders(int customerId)
    {
        var data = from c in Orders
                   where c.CustomerID == customerId
                   group c by new { c.CustomerID, c.ItemID,c.Description,c.POST,c.Cost } into g
                   select new OrderEntity () {
                      CustomerID = g.Key.CustomerID,
                      ItemID =  g.Key.ItemID,
                      Quantity = g.Sum(x => x.Quantity),
                      Description = g.Key.Description,
                      POST = g.Key.POST,
                      Cost = g.Key.Cost 
                   };
        return data.ToList();
    }

C＃EntityFramework加入

1 个答案: