Question

我使用的是Asp.Net Entity Framework。我有2个表，我想在不同表中的两个变量之间做一个减号。我加入了但是没有用。这是我的代码：

var prod_items = (from prod in entity.ProductSet 
                  join ca in entity.CartSet 
                  on prod.ProductID equals ca.Product_ProductID 
                  where ca.Customer_CustomerID.Equals(id) 
                  select new { ca.Quantity,prod.ProductStock,prod.ProductID });
int h;

foreach (var nbr in prod_items) 
{
    h = nbr.ProductStock - nbr.Quantity;
    ProductSet p = entity.ProductSet
                         .Where(i => i.ProductID == nbr.ProductID)
                         .FirstOrDefault();
    p.ProductStock = h;
}

我收到的错误如ArgumentException未被用户代码处理。

Answer 1

您可以尝试这样的事情：

var prod_items = (from prod in entity.ProductSet 
                  join ca in entity.CartSet 
                  on prod.ProductID equals ca.Product_ProductID 
                  where ca.Customer_CustomerID.Equals(id) 
                  select new ProductSet 
                  {
                      ProductID = prod.ProductID,
                      ProductStock =  prod.ProductStock - ca.Quantity,
                      // Set the values for th rest properties.
                  });

从两个表中获取字段之间的数学差异

1 个答案: