数据库中的数据到C#代码中的数值要注意转换了

如下，从数据库的存储过程传值过去给C#，如果不再转换一次，C#接收到的值就会有问题，我原来传了一个17800.15,c#中接收到成了17800.156，怎么搞都不对。
ActualAmount数据库中定义的是decimal(18,2)

数据库中

ALTER PROCEDURE [dbo].[P_Sys_GetCFPGStageSum]
	-- Add the parameters for the stored procedure here	
	--@CompanyID nvarchar(50),
	--@ContractID nvarchar(50),
	@OrderID nvarchar(50)
	--@StageId nvarchar(50),
	--@StageAmount numeric(18,2),
	--@BFB nvarchar(50),
	--@Playtime DATETIME,
 --   @StageDes nvarchar(150),
	----@GotAmount numeric(18,2),--已收
	--@CurrentAmount numeric(18,2),--当前收款	
	--@CreatedByUserID nvarchar(50),
	--@WBSID nvarchar(50)
AS
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	select ISNULL(SUM(ActualAmount),0) from [T_SaleConfirmStage]
	where OrderID =@OrderID and IsDeleted=0	
		END



	
END
 

代码中

    public float GetCFPGStageSum(string DDH)
        {
            float iResult = 0;
            using (IDataContext ctx = DataContext.Instance())
            {
                iResult = ctx.ExecuteScalar<float>(System.Data.CommandType.StoredProcedure,
                    "[P_Sys_GetCFPGStageSum]", DDH);
            }
            return iResult;
        }

后来改成解决

ALTER PROCEDURE [dbo].[P_Sys_GetCFPGStageSum]
	-- Add the parameters for the stored procedure here	
	--@CompanyID nvarchar(50),
	--@ContractID nvarchar(50),
	@OrderID nvarchar(50)
	--@StageId nvarchar(50),
	--@StageAmount numeric(18,2),
	--@BFB nvarchar(50),
	--@Playtime DATETIME,
 --   @StageDes nvarchar(150),
	----@GotAmount numeric(18,2),--已收
	--@CurrentAmount numeric(18,2),--当前收款	
	--@CreatedByUserID nvarchar(50),
	--@WBSID nvarchar(50)
AS
BEGIN
	-- SET NOCOUNT ON added to prevent extra result sets from
	-- interfering with SELECT statements.
	--rzp20150126------------------------------------------------------------------------
	--select ISNULL(SUM(ActualAmount),0) from [T_SaleConfirmStage]
	--where OrderID =@OrderID and IsDeleted=0
	
	select CONVERT(DECIMAL(18,2), ISNULL(SUM(ActualAmount),0)) from [T_SaleConfirmStage]
	where OrderID =@OrderID and IsDeleted=0
	-------------------------------------------------------------------------------------