/// <summary>
 /// (DB)依SQL指令取得資料結果(一個字串)
 /// </summary>
 public string _DB_GetStr(string strSql, bool cache = false, int cacheSeconds = 60)
 {
     if (cache && cacheSeconds > 0)
     {
         cacheDatas.RemoveAll(x => x.createTime < DateTime.Now.AddSeconds(cacheSeconds * -1));
         var result = cacheDatas.Find(x => x.strSql == strSql);
         if (result == null)
         {
             var str = DBC.GetSQLCmd_Str(strSql);
             cacheDatas.Add(new CacheData()
             {
                 strSql     = strSql,
                 resultStr  = str,
                 createTime = DateTime.Now
             });
             return(str);
         }
         else
         {
             return(result.resultStr);
         }
     }
     else
     {
         return(DBC.GetSQLCmd_Str(strSql));
     }
 }