LINQ to Entities 查询不支持转换为十进制

我有一个数据库表事务（transactionID，LocalAmount ...）。其中 Localmount 属性的数据类型是float。在用户界面上我试图返回SUM按钮单击事件中一行中的列 (Localamount)。

我用过decimal代替float

但是我在转换到的代码上遇到错误decimal

System.NotSupportedException was unhandled by user code
Message=Casting to Decimal is not supported in LINQ to Entities queries, because the required precision and scale information cannot be inferred.

The

 public static IEnumerable<TransactionTotalForProfitcenter> GetTotalTransactionsForProfitcenter(int profitcenterID)
    {
        List<TransactionTotalForProfitcenter> transactions = new List<TransactionTotalForProfitcenter>();
        using (var context = new CostReportEntities())
        {
          transactions = (from t in context.Transactions
                            join comp in context.Companies on t.CompanyID equals comp.CompanyID
                            join c in context.Countries on comp.CountryID equals c.CountryID
                            where c.CountryID.Equals(comp.CountryID) && t.CompanyID == comp.CompanyID 
                             
                            join acc in context.Accounts
                                 on t.AccountID equals acc.AccountID
                            join pc in context.Profitcenters
                                on t.ProfitcenterID equals pc.ProfitcenterID
                            group t by pc.ProfitcenterCode into tProfitcenter
                            
                            select new TransactionTotalForProfitcenter
                            {
                                ProfitcenterCode = tProfitcenter.Key,
                    //the error is occurring on the following line           
                                TotalTransactionAmount = (decimal)tProfitcenter.Sum(t => t.LocalAmount),  
                   //the error is occurring on the following line       
                                TotalTransactionAmountInEUR = (decimal)tProfitcenter.Sum(t => t.AmountInEUR) //the error is occurring on this line 
                            }
                            ).ToList();

        }
        return transactions;

    }

我尝试了以下帖子中的一些选项，但没有成功。

• LINQ to SQL 奇怪的浮点行为 https://stackoverflow.com/a/1817557/1108500
• 从十进制转换为浮点型 https://stackoverflow.com/a/1817557/1108500

谁能指出我可以尝试哪些其他选择。如果我对 LINQ 的了解太微不足道，请原谅我。

实体框架表明它不支持您想要的转换。一种解决方法是简单地在数据库中执行尽可能多的工作，然后在内存中完成该过程。在您的情况下，您可以以其本机类型计算总和，将结果作为匿名类型拉入内存，然后在构造实际需要的类型时执行转换。要获取原始查询，您可以进行以下更改：

select new // anonymous type from DB
{
    ProfitcenterCode = tProfitcenter.Key,
    // notice there are no conversions for these sums
    TotalTransactionAmount = tProfitcenter.Sum(t => t.LocalAmount),       
    TotalTransactionAmountInEUR = tProfitcenter.Sum(t => t.AmountInEUR)
})
.AsEnumerable() // perform rest of work in memory
.Select(item =>
     // construct your proper type outside of DB
    new TransactionTotalForProfitcenter
    {
        ProfitcenterCode = item.ProfitcenterCode,
        TotalTransactionAmount = (decimal)item.TotalTransactionAmount
        TotalTransactionAmountInEUR = (decimal)item.TotalTransactionAmountInEUR
    }
).ToList();