mvc4 - db.SaveChanges() - 小数值超出范围

我正在构建一个 MVC4 应用程序，它要求我在“创建”新记录时生成 21 位密钥。

这是我定义数据库列的上下文：

public class cust
    {
        public int ID { get; set; }

        public decimal CPCUST_KEY { get; set; }

        public decimal CPCUST_TOKEN { get; set; }

        public decimal CPCUST_ALTERNATE_KEY { get; set; }

在我的 SQL Server 表中，项目全部设置为“十进制(38, 0)”...我相信我应该使用十进制数据类型？不知怎的，我仍然收到下面的超出范围错误。我的号码完全在 SQL 变量的 38 位最大长度之内。

System.Data.Entity.Infrastructure.DbUpdateException was unhandled by user code
  HResult=-2146233087
  Message=An error occurred while updating the entries. See the inner exception for details.
  Source=EntityFramework
  StackTrace:
       at System.Data.Entity.Internal.InternalContext.SaveChanges()
       at System.Data.Entity.Internal.LazyInternalContext.SaveChanges()
       at System.Data.Entity.DbContext.SaveChanges()
       at Portal.Controllers.custController.Create(cust cust) in c:\Users\mwallace\Documents\Visual Studio 2012\Projects\Portal\Portal\Controllers\custController.cs:line 56
       at lambda_method(Closure , ControllerBase , Object[] )
       at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
       at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters)
       at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.InvokeSynchronousActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41()
       at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _)
       at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End()
       at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass37.<>c__DisplayaClass39.<BeginInvokeActionMethodWithFilters>b__33()
       at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49()
  InnerException: System.Data.UpdateException
       HResult=-2146233087
       Message=An error occurred while updating the entries. See the inner exception for details.
       Source=System.Data.Entity
       StackTrace:
            at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
            at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache)
            at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options)
            at System.Data.Entity.Internal.InternalContext.SaveChanges()
       InnerException: System.ArgumentException
            HResult=-2147024809
            Message=Parameter value '137090248607999999999.00' is out of range.
            Source=System.Data
            StackTrace:
                 at System.Data.SqlClient.TdsParser.TdsExecuteRPC(_SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc, Boolean sync, TaskCompletionSource`1 completion, Int32 startRpc, Int32 startParam)
                 at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite)
                 at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)
                 at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method)
                 at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method)
                 at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior)
                 at System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior)
                 at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator translator, EntityConnection connection, Dictionary`2 identifierValues, List`1 generatedValues)
                 at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter)
            InnerException: 

这是 Visual Studio 在崩溃时带我到的 db.SaveChanges() 行。

// POST: /cust/Create

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create(cust cust)
{
    if (ModelState.IsValid)
    {
        db.cpcust.Add(cust);
        db.SaveChanges();
        return RedirectToAction("Index");
    }

    return View(cust);
}

发现这两个线程之间的交易是什么：

如何使用 EntityFramework 4.1 CodeFirst 防止小数值在保存时被截断为 2 位？ https://stackoverflow.com/questions/6629263/how-do-i-prevent-decimal-values-from-being-truncated-to-2-places-on-save-using-t

EF Code First 中的小数精度和小数位数 https://stackoverflow.com/questions/3504660/entity-framework-code-first-decimal-precision-and-scale

具体将此代码应用于我的：

public class MyContext : DbContext
{
    public DbSet<Metrics> Metrics { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Metrics>().Property(x => x.PPM).HasPrecision(4, 3);
    }
}