How to implement a standalone application?

Question

Database

Good afternoon!
There is a client - server application built using WCF.
How can I make my application work offline without connecting to WCF?
There was an idea to make a copy of the database from the server via WCF channels to the user's PC (with the necessary information) and work with it, but here 2 questions creep in: desynchronization in the database, the server database id and client database id will not match, which is critical for this application.
Tell me a way out of the situation when access to WCF is closed (there is no communication channel)

Answer 1

When adding records to a local table, set their id above 1 billion.
When a connection appears, make a selection based on such data and send it to the server.
Return the result [{oldid, newid}, ...] and update the id for the entries.
In the server database, add the "last update time" field, this is to receive
only changed data from the server.