Most states keep all data in a state-wide database and all registers are electronically connected. This is the reason why you don't need to deregister anymore w

Most states keep all data in a state-wide database and all registers are electronically connected. This is the reason why you don't need to deregister anymore when moving within Germany, a new registration will suffice. What there isn't is a single central database and if you want to query data you will need to ask different authorities to get it all.