The Qt5 docs for building the plugins are different from the Qt4 docs..

http://qt-project.org/doc/qt-4.8/sql-driver.html#qoci
https://qt-project.org/doc/qt-5.1/qt...iver.html#qoci

This is why you should refer the original docs and not some blow-by-blow 'tutorial' that tells you little more but will be out-of-date quickly.