产生随机不重复ID

 /// <summary>
        /// Decimal 27位ID生成规则（前面17位为时间，后面10位为随机生成数）：
        /// </summary>
        /// <returns></returns>
        public decimal GeneratePk()
        {
            Guid id = Guid.NewGuid();
            byte[] byid = id.ToByteArray();

            uint uid = BitConverter.ToUInt32(byid, 12);
            string strid = DateTime.Now.ToString("yyyyMMddHHmmssfff") + uid.ToString("D10");

            return decimal.Parse(strid);
        }