在C#中利用adodb调用oracle中定义的函数，如何实现？

Question

例如一个很简单的函数：
 FUNCTION testf (x IN VARCHAR2)
      RETURN VARCHAR2
   IS
   BEGIN
      RETURN x || '-server';
   END;

Answer 1

调用存储过程，我利用下面的代码能实现：
ADODB.Command adoCmd;
 GeneralCommon.M_CN1.CursorLocation = ADODB.CursorLocationEnum.adUseServer;
                adoCmd = new ADODB.Command();                Conn.BeginTrans();                adoCmd.ActiveConnection = GeneralCommon.M_CN1;
                adoCmd.CommandType = ADODB.CommandTypeEnum.adCmdStoredProc;
                adoCmd.CommandText = Proce_Name;                //Ceate Input Parameter
                for (iCount = 0; iCount <= Para_Info.Length - 1; iCount++)
                {
                    adoCmd.Parameters.Append(adoCmd.CreateParameter("", ADODB.DataTypeEnum.adVariant, ADODB.ParameterDirectionEnum.adParamInput, 0, null));
                }                //Input Parameters Value Setting
                for (iCount = 0; iCount <= Para_Info.Length - 1; iCount++)
                {
                    adoCmd.Parameters[iCount].Value = Para_Info[iCount];
                }
                object value = null;
                
                adoCmd.Parameters.Append(adoCmd.CreateParameter("arg_e_code", ADODB.DataTypeEnum.adInteger, ADODB.ParameterDirectionEnum.adParamOutput, 1, value));
                adoCmd.Parameters.Append(adoCmd.CreateParameter("arg_e_msg", ADODB.DataTypeEnum.adVarChar, ADODB.ParameterDirectionEnum.adParamOutput, 256, value));
                adoCmd.Execute(out value);                //Process Error Check
                if (adoCmd.Parameters["arg_e_code"].Value.ToString() != "0")
                {
                   
                    ret_Result_ErrCode =int.Parse( adoCmd.Parameters["arg_e_code"].Value.ToString());
                    ret_Result_ErrMsg = (string)(adoCmd.Parameters["arg_e_msg"].Value);
                    Conn.RollbackTrans();//1123
                    sErrMessg = (string)("Error Code : " + ret_Result_ErrCode + "\r\n" + "Error Mesg : " + ret_Result_ErrMsg);
                    Gp_MsgBoxDisplay(sErrMessg, "", "");
                    returnValue = false;
                }
                else
                {
                    Conn.CommitTrans();
                    returnValue = true;
                }                adoCmd = null;
                Cursor.Current = Cursors.Default;                if (GeneralCommon.M_CN1.State != 0)
                {
                    GeneralCommon.M_CN1.Close();
                }
            }
            catch (Exception ex)
            {
                adoCmd = null;
                Conn.RollbackTrans();
              
              
            }            return returnValue;

Answer 2

select testf('x') from dual