//獲取上個月第一天
Convert.ToDateTime(DateTime.Now.AddDays(1 - DateTime.Now.Day).AddMonths(-1).ToLongDateString()).ToString(“yyyy-MM-dd HH:mm:ss”);
//獲取上個月最後一天
Convert.ToDateTime(DateTime.Now.AddDays(1 - DateTime.Now.Day).AddDays(-1).ToLongDateString()).AddDays(1).AddMilliseconds(-1).ToString(“yyyy-MM-dd HH:mm:ss”);