We couldn't reproduce the problem.
Please send us (mydac*crlab*com) a complete small sample to demonstrate it and include script to create and fill table.
Also supply us following information
- Exact version of MyDAC (3.55.X.XX). You can see it in About sheet of TMyConnection Editor
- Exact version of Delphi, C++ Builder or Kylix
- Exact version of MySQL server and MySQL client.
You can see it in Info sheet of TMyConnection Editor