private MySqlGuid ReadOldGuid(MySqlPacket packet, long length)
{
if (length == -1)
length = (long)packet.ReadFieldLength();
byte[] buff = new byte[length];
packet.Read(buff, 0, (int)length);
MySqlGuid g = new MySqlGuid(buff);
g.OldGuids = OldGuids;
return g;
}