GetNewDataTable

　　　　 public static DataTable GetNewDataTable(DataTable dt, string condition)
        {
            DataTable newdt = new DataTable();
            newdt = dt.Clone();
            DataRow[] dr = dt.Select(condition);
            for (int i = 0; i < dr.Length; i++)
            {
                newdt.ImportRow((DataRow)dr[i]);
            }
            return newdt;//返回的查询结果
        }