Hello,

I wrote an php/mysql/apache application used by 7-8 users on a local network. After a while the client open another location and there I made the same structure: local network, 7-8 users, same application. On that moment a syncronization wasn't neccesary. After another period of time the client open the third location and connect the location through VPN. Now the syncronization between mysql servers are highly requested one time per hour. What should I do?

I don't want to make one single mysql server because, here, in Romania (my country), is very possible that the VPN connection to be offline in a moment or another and that thing will cause activity break of my client.

The solution that I have in mind is to set up a mysql server on every location and a master server. Users will insert data on slaves and I want that every mysql servers to be syncronized with master once in an hour. I made some tests with SQLyog 3.63 and all i got is a sincronization master-slave which means: all records that exists on master will be writen on slaves but all records that exists on slaves are deleted.

Any help will be appreciated...
Thanks.

This is not possible because MySQL has only master->slave replication implemented.
Try to solve your problem on application tier.