C++ connectivity to Oracle

Hello everybody. I'm a student in computer science and I am currently working in a 8-people team in order to complete a 6-month project.

We need Oracle 9i database access, but it's not provided by Qt2.3, the toolkit we will use to ensure portability. We can't ever dream of buying Qt3,
for obvious reasons.

I need a library to connect to an Oracle database in C++.

It needs to work on Windows, Linux and MacOsX. If possible, it should be free (free software would even be better, because then
we could adapt it if needed).

Thanks in advance to anybody who as much as tries to help :)

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Non serviam!