Db-CombinedGuid

CombinedGuid.cs

//
// Used to create a Combined GUID for database Primary Keys
//
public Guid GenerateComb()
{
  // T-SQL Equivalent
  // DECLARE @guid UNIQUEIDENTIFIER;
  // SET @guid = CAST(CAST(NEWID() AS BINARY(10)) + CAST(GETDATE() AS BINARY(6)) AS UNIQUEIDENTIFIER);
  // SELECT @guid;

  byte[] destinationArray = Guid.NewGuid().ToByteArray();
  DateTime time = new DateTime(0x76c, 1, 1);
  DateTime now = DateTime.Now;
  TimeSpan span = new TimeSpan(now.Ticks - time.Ticks);
  TimeSpan timeOfDay = now.TimeOfDay;
  byte[] bytes = BitConverter.GetBytes(span.Days);
  byte[] array = BitConverter.GetBytes((long) (timeOfDay.TotalMilliseconds / 3.333333));
  Array.Reverse(bytes);
  Array.Reverse(array);
  Array.Copy(bytes, bytes.Length - 2, destinationArray, destinationArray.Length - 6, 2);
  Array.Copy(array, array.Length - 4, destinationArray, destinationArray.Length - 4, 4);
  return new Guid(destinationArray);
}