SqlDataReader指定转换无效的解决方法

//获取最新显示顺序数据

      stringstr =string.Format(@"if exists(select ShowOrder from GIS_FuncDefaultLayer where GISFuncId = {0})

                           select max(ShowOrder) as ShowOrder from GIS_FuncDefaultLayer where GISFuncId ={0}

                           else select Ɔ' as ShowOrder", GISFuncId);

      IDataReader dataReader = helper.ExecuteReader(CommandType.Text, str);

      if(dataReader.Read())//判断当前功能Id下是否有数据

      {

        //读取赋值

        try

        {

          showOrder = dataReader.GetInt32(0);

        }

        catch(Exception ex)

        {

          HttpResponseMessage result =newHttpResponseMessage { Content =newStringContent(ex.Message) };

          returnresult;

        }

      }

dataReader.Close();//关闭

//解决

showOrder=int.Parse(dataReader.GetString(0));