When you get a "big subject" query like this, the first thing to do is to start by looking at Google:
"database synchronization"[
^] and trying to work out if you can either find a solution there, or at least eliminate some options to make the question smaller and "more answerable". Have a look at some of the links, and see what fits your circumstances - there are so many options that could be what you are trying to achieve that anything we suggest at this stage is almost certainly wrong! :laugh: