Here you need to understand two points
1)A Book Store App (which is a web application) made on PHP and MySQL is running on local wamp server(in one computer locally) for store's proprietary use, which is running fine.
2)I stucked with implementing online(Internet) version of web app for online reservations of books and customers collect books which are reserved online from Store by paying money in store.
Now if you understood the scenerion, my question is what is the best way to update Local MySQL Database, when some one reserved a book in online version of web application.
Note that one answer for this is integrating local version of webapp into online version, but it shud not be done.
Except above answer experts please guide me with
how to design a secure updation of local MySQL Database from online MySQL database or
how to send data from a PHP script to two databases securely
Which implementation is best and please do provide some pros and cons. Thanks in advance.