What I meant was that when a client goes online, the database looks for something that says what they have changed whilst offline. When it finds that information, the app then sends those changes to their places in the online database. The same thing would then happen from online to offline.
You could do this with some kind of XML file or maybe in a database table with one row per client, which contains the information as to what has been updated.
This technique would sort of be like git or svn, but not as complex. It remembers which values have been changed, but not the new or old values.
hi, using PHP for offline apps is not common, you can try other languages for windows and mac applications and for sync data you can provide services for your desktop apps from your main web application which is published online.