Question

我有一个这样的存储过程，当我在SQL Server Management Studio中运行此存储过程时，我只获得“命令已成功完成。”

如果在我的vb.net代码中使用简单的if语句，我可以检查@onum是否为0。

我从不使用这种类型，通常存储过程在没有值时返回空行。

 ALTER PROCEDURE [dbo].[o_By_RNum]
     @rNum varchar(50)
     ,@ServiceType varchar(50)
     ,@Direction varchar(1) = NULL
     ,@VendorID int
AS
   Declare @onum int

   If @Direction is Null
   Begin
      SELECT @onum = o_num
      FROM RemoteOrder
      WHERE r_num LIKE @rNum
        AND r_ServiceType = @ServiceType
        AND VendorID = @VendorID
   End
   Else
   Begin
      SELECT @onum = o_num
      FROM RemoteOrder
      WHERE r_num LIKE @rNum
        AND r_ServiceType = @ServiceType
        AND Direction = @Direction
        AND VendorID = @VendorID
   End

   RETURN ISNULL(@onum,0)

我在我的vb.net代码中调用这个存储过程，如下所示：

Private Sub DLL_GetOnumFromRemoteOrder_By_RNum(ByRef SqlConn As SqlConnection, ByRef R_NUM As String, ByRef R_SERVICETYPE As String, ByRef DIRECTION As String, ByRef VENDORID As Integer, ByRef RetVal As Integer)

    'Open the SQL Connection
    If SqlConn.State <> ConnectionState.Open Then SqlConn.Open()

    'Add Parameters
    Dim command As New SqlCommand("DLL_GetOnumFromRemoteOrder_By_RNum", SqlConn)
    command.CommandType = CommandType.StoredProcedure
    command.Parameters.Add("@rNum", SqlDbType.VarChar).Value = IIf(IsNothing(R_NUM), DBNull.Value, R_NUM)
    command.Parameters.Add("@ServiceType", SqlDbType.VarChar).Value = IIf(IsNothing(R_SERVICETYPE), DBNull.Value, R_SERVICETYPE)
    command.Parameters.Add("@Direction", SqlDbType.Char).Value = IIf(IsNothing(DIRECTION), DBNull.Value, DIRECTION)
    command.Parameters.Add("@VendorID", SqlDbType.Int).Value = IIf(IsNothing(VENDORID), DBNull.Value, VENDORID)

    command.Parameters.Add("@RETURN_VALUE", SqlDbType.Int)
    command.Parameters("@RETURN_VALUE").Direction = ParameterDirection.ReturnValue

    'Dim dr As SqlDataReader
    'dr = command.ExecuteReader()
    'dr.Read()
    'Return dr
    'Execute the command
    RetVal = command.ExecuteNonQuery()
    RetVal = CInt(command.Parameters.Item("@RETURN_VALUE").Value)
End Sub

Answer 1

将存储过程更改为：

 ALTER  PROCEDURE [dbo].[o_By_RNum]

 @rNum varchar(50)
,@ServiceType varchar(50)
,@Direction varchar(1) = NULL
,@VendorID int
 AS
 BEGIN

    SELECT ISNULL(o_num,0)
    FROM RemoteOrder
    WHERE r_num LIKE @rNum
    AND r_ServiceType = @ServiceType
    AND (@Direction is Null OR Direction = @Direction)
    AND VendorID = @VendorID
  END

这样您将拥有将在Management Studio中显示结果的实际SELECT。

然后代替

之后的最后4行

command.Parameters.Add("@VendorID", SqlDbType.Int).Value = IIf(IsNothing(VENDORID), DBNull.Value, VENDORID)

添加RETURN_VALUE参数和ExecuteNonQuery只需

RetVal = command.ExecuteScalar()

Answer 2

问题似乎出现在return参数的声明中，因为没有必要给它一个名字或类型，因为返回值总是一个int。 This question也有同样的问题。他们建议的代码是这样的：

Dim RetvalParameter As SqlParameter = command.Parameters.Add()
RetvalParameter.Direction = ParameterDirection.ReturnValue

command.ExecuteNonQuery()
RetVal = CInt(RetvalParameter.Value)

检查从存储过程返回的字段是否有值？

2 个答案: