First of all, thanks for your quick reply.
I have an application installed on a PC in my store that uses MSSQL Database (Express Edition) and I want to synchro with Prestashop 1.7.3.1
The aim is to maintain the same stock in both sides. If a user buy online the stock must reduce in mysql and mssql, and if I sale a product in the store it must be reflected in mssql and mysql.
I don't know how to use webservices, if you have documentation that a I can read, just tell me, or If you know any solution to reach the aim.
Thanks in advance