The official documentation should do the trick, not for me:
cd $QTDIR/qtbase/src/plugins/sqldrivers
qmake -- OCI_INCDIR=/usr/include/oracle/10.1.0.3/client OCI_LIBDIR=/usr/lib/oracle/10.1.0.3/client/lib
make sub-oci
What I have tried:
cd /opt/Qt5/qtbase/src/plugins/sqldrivers
qmake -- OCI_INCDIR=/opt/oracle/db/prod/12.2.0/rdbms/public OCI_LIBDIR=/opt/oracle/db/prod/12.2.0/lib
make sub-oci
They assume that we have installed the RPM packages of the Instant Client Package SDK and I'm not in this case. I don't know how the client was installed, but I have no installed packages names Oracle.