SqlDataReader指定轉換無效的解決方法

//獲取最新顯示順序數據
 string str = 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 '0' as ShowOrder", GISFuncId); 
 IDataReader dataReader = helper.ExecuteReader(CommandType.Text, str);
 if (dataReader.Read())//判斷當前功能Id下是否有數據
 {
 //讀取賦值
 try
 {
 showOrder = dataReader.GetInt32(0);
 
 }
 catch (Exception ex)
 {

 HttpResponseMessage result = new HttpResponseMessage { Content = new StringContent(ex.Message) };
 return result;
 }
 
 }
dataReader.Close();//關閉

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