/* GetDataTable方法需要自己写，传入一个查询语句返回一个datatable */

        /// <summary>        /// 获取分页数据        /// </summary>        /// <param name="PageIndex">页码</param>        /// <param name="countPerPage">每页条数</param>        /// <param name="columns">返回结果集的列名集合以逗号隔开</param>        /// <param name="sqlstr">查询语句</param>        /// <returns></returns>        public DataTable GetPageData(int PageIndex, int countPerPage, string columns, string sqlstr)        {            DataTable dt = new DataTable();            //起始条数            int startRow = (PageIndex - 1) * countPerPage + 1;            //结束条数            int endRow = PageIndex * countPerPage;            string selectStr = "select " + columns + " from (select   rownum  rownumber ," + columns + "  from (" + sqlstr + ") A ) B where rownumber  between " + startRow + " and " + endRow;            dt = GetDataTable(selectStr);            return dt;        }