/// <summary>

        /// 保留GUID的10个字节，用另6个字节表示GUID生成的时间（DateTime）组合方式

        /// </summary>

        /// <returns></returns>

        public static Guid GenerateComb()

        {

            byte[] guidArray = Guid.NewGuid().ToByteArray();

            DateTime baseDate = new DateTime(, , );

            DateTime now = DateTime.Now;

            // Get the days and milliseconds which will be used to build

            //the byte string

            TimeSpan days = new TimeSpan(now.Ticks - baseDate.Ticks);

            TimeSpan msecs = now.TimeOfDay;

            // Convert to a byte array

            // Note that SQL Server is accurate to 1/300th of a

            // millisecond so we divide by 3.333333

            byte[] daysArray = BitConverter.GetBytes(days.Days);

            byte[] msecsArray = BitConverter.GetBytes((long)

                (msecs.TotalMilliseconds / 3.333333));

            // Reverse the bytes to match SQL Servers ordering

            Array.Reverse(daysArray);

            Array.Reverse(msecsArray);

            // Copy the bytes into the guid

            Array.Copy(daysArray, daysArray.Length - , guidArray,

                guidArray.Length - , );

            Array.Copy(msecsArray, msecsArray.Length - , guidArray,

                guidArray.Length - , );

            return new Guid(guidArray);

        }

        /// <summary>

        /// 根据GUID获取19位的唯一数字序列

        /// </summary>

        public static long GuidToLong()

        {

            byte[] buffer = Guid.NewGuid().ToByteArray();

            return BitConverter.ToInt64(buffer, );

        }