I see no benefit to the proposed system. If an individual voter can go into the database and verify how his vote was recorded, then the ballot is not secret. The data is in the database and is available to anyone with access to the database.
The ballot will be relatively secret because each voter will be coded.For example you come to vote to polling
station and after checking your ID you are allowed to proceed to voting computer.You enter any combination of digits
and letters such as Ab74H982LM and computer checks if there is no such combination already.If it`s OK than you proposed
to make a choice from parties to vote.You mark party of your choice and computer accepts it.After that your choice is
displayed in a database such as Ab74H982LM - REPUBLICANS.Except you NOBODY suppose to know that this combiation
of numbers is YOU.
You put a lot of faith into the government to control the database, but what if the government is a corrupt regime, which wants to fix the election?
Dictotoral regimes usually do not conduct votes at all or just will not accept the proposed system.This system is designed for countries which pretend to be civilized or make firs steps in democrasy.And in which governments afraid to be
caught on open fraud.
If there are fraudulent voters registrations, your system will not help matters. Sure it could tell if more people voted than were registered, but then what? You have no way of sorting out the bad votes from the good.
If there will be more voters in the database than it supposed to be,well then at least pople will know exact magnitude of fraud and could apply in court.If votes are conducted in proper way, then multiple voting is not easy.Usually each poling station has predetermined number voters and mark down each voter who came to vote.If there is multiple voters then each particular voting station should detect and know it.Also another methods of fraud prevention may be used.
For examle the databes could be designed in the way that it just does`t suppose to accept suspicious or multiple voters.