I have a 32-bit application that must run on a Windows x64 server using a 64-bit version of MySQL.
Should I use a 32-bit ODBC driver or a 64-bit ODBC driver?
Or should I install a 32-bit version of MySQL too?
You would need to install a 32-bit SQL and ODBC driver seeing as how your application is in 32-bit. For compatibility reasons.
I am still searching, will edit.
** EDIT
To work around this problem, use the appropriate version of the ODBC Administrator tool. If you build and then run an application as a 32-bit application on a 64-bit operating system, you must create the ODBC data source by using the ODBC Administrator tool in %windir%\SysWOW64\odbcad32.exe. To indicate the type of DSN, you can add "_32" to the 32-bit user DSNs and "_64" to the 64-bit user DSNs.
From Microsoft support.
** EDIT
If you want to have a workaround, you need to create you ODBC data source by using the Admin tool found in. This is also explained in the same link.
%windir%\SysWOW64\odbcad32.exe