Hello Radek,

It's not possible to use MySQL as a source at the present moment.  The only sources that can be used to import product catalogues are text and CSV files:

http://help.websitex5.com/en/v12/evo/index.html?carrello_importa_esporta.htm

Please consider opening an 'Idea' post in order that the developers might consider including MySQL support in a future update/upgrade.

Kind regards,

Paul