Well to answer your questions:
What will happen? How to deal with it ?
As soon he recycled the database you will loose everything on your FMGS, which means V2 as well. So the first thing you will notice that you will have to carry out NO FD's take off procedure. If you are not aware of the procedure (it is MEL item, but you would have reviewed it before take off), either reject take off or carry out Unreliable Airspeed memory item and get to safe altitude before doing anything else.
This brings you to your second problem, now that you are at safe altitude you cannot carry out cleared SID or carry on to your FPR if you were on RNAV SID. So I'd request radar vectors towards the first VOR on the SID and carry out raw data flying. Once you are happily flying towards the VOR, reinsert all the data again in the FMGS including GW/CG and FOB, now you can perform direct to function and engage the autopilot. At this time give the dirtiest possible look to the Check pilot and ask him what the F was he/she thinking carrying out a stunt like that.
The best solution, given your level of experience, "You have control." and after landing write a letter to your Chief Pilot Training, I'm sure it is not part of the training syllabus.