Bruce,
As a told you, my DB was very old and there were many differents fields, with different properties, like type, size, length, etc. and I needed to update them.
As you said me, these were not necessary, but I would like to have a clean DB and with the actual version.
Well, I'm very and extremely happy, because I did and it was a success !
Therefore, I've just shared this for help anothers.
It was only a post for share an idea, but if you don't think so, it is fine.
Sorry for that and thanks a lot for your concern.
Regards.