linq 调用 有返回值（numeric）的存储过程，报错“从数据类型 numeric 转换为 numeric 时出错”

现象：

Linq To Entity 调用 有numeric返回值的存储过程，报错“从数据类型 numeric 转换为 numeric 时出错”

前提：

存储过程

Create PROCEDURE [dbo].[ENC_GetRangeTotalEnergy]
-- Add the parameters for the stored procedure here
@StartTime datetime,
@EndTime datetime,
@channelIds varchar(8000),
@result numeric(18,2) output-- 返回参数
AS
BEGIN

select top 1 @result=(sum(Maxvalue)-sum(Minvalue))  from
(
select chid ChannelId, min(value) Minvalue,max(value) Maxvalue from dbo.DTM_History
where time between @StartTime and @EndTime and value >0
and chid in
(
select * from STM_SplitSTR(@channelIds,',')
)
group by chid
) TempTable

if(@result is null)
set @result=0
END

程序调用代码：(报错 “从数据类型 numeric 转换为 numeric 时出错”)

ObjectParameter resultParameter = new ObjectParameter("result",0);

// other Statement
this.ObjectContext.ENC_GetRangeTotalEnergy(startDate, endDate, string.Join(",", channelIdList), resultParameter);

分析过程：

1.确定数据库存储过程是否正确

调用存储过程的测试SQL（执行成功无问题）

DECLARE @RC int
DECLARE @StartTime datetime='2012/7/1 0:00:00'
DECLARE @EndTime datetime='2012/8/1 0:00:00'
DECLARE @channelIds varchar(8000)='f16061a7-dfe9-4dd8-b780-c2355ba9167b,73f5085d-937b-4726-9c2d-7f821fe63646'
DECLARE @result decimal(18,2)

-- TODO: 在此处设置参数值。

EXECUTE @RC = [Linsanity].[dbo].[ENC_GetRangeTotalEnergy]
@StartTime
,@EndTime
,@channelIds
,@result OUTPUT

select @result
GO

2.对比错误的SQL语句

SQL Server Profiler 监测到程序发送的SQL(报错 “从数据类型 numeric 转换为 numeric 时出错”)

declare @p4 numeric(1,0)
set @p4=0
exec [dbo].[ENC_GetRangeTotalEnergy] @StartTime='2012-07-01 00:00:00',@EndTime='2012-08-01 00:00:00',@channelIds='f16061a7-dfe9-4dd8-b780-c2355ba9167b,73f5085d-937b-4726-9c2d-7f821fe63646',@result=@p4 output
select @p4

这里可以看到，@p4 的类型为 numeric(1,0),类型不符合，所以报错

解决方案一：

1.修改linq调用部分

ObjectParameter resultParameter = new ObjectParameter("result",typeof(decimal));

// other Statement
this.ObjectContext.ENC_GetRangeTotalEnergy(startDate, endDate, string.Join(",", channelIdList), resultParameter);

2. 修改.edmx文件中存储过程参数部分（添加红色部分，确保有两位小数）

<Function Name="ENC_GetRangeTotalEnergy" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="false" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo">
<Parameter Name="StartTime" Type="datetime" Mode="In" />
<Parameter Name="EndTime" Type="datetime" Mode="In" />
<Parameter Name="channelIds" Type="varchar" Mode="In" />
<Parameter Name="result" Type="numeric" Mode="InOut"  Precision="18" Scale="2" />
</Function>

解决方案二：

修改存储过程，把返回值的类型设置为varchar类型，然后在程序中转换为numberic类型

修改后的存储过程

CREATE PROCEDURE [dbo].[ENC_GetRangeTotalEnergy]
-- Add the parameters for the stored procedure here
@StartTime datetime,
@EndTime datetime,
@channelIds varchar(8000),
@result varchar(100) output
AS
BEGIN
declare @resultNumber decimal(18,2)
select top 1 @resultNumber=(sum(Maxvalue)-sum(Minvalue))  from
(
select chid ChannelId, min(value) Minvalue,max(value) Maxvalue from dbo.DTM_History
where time between @StartTime and @EndTime and value >0
and chid in
(
select * from STM_SplitSTR(@channelIds,',')
)
group by chid
) TempTable

if(@resultNumber is null)
set @resultNumber=0
set @result=cast(@resultNumber as varchar(100))
END