Hi All!
I need help on this issue:

My new client run an old windows application for manage a gym.
This application in written in VB and use more DBF file for store data.
Into these files there are the lession schedule and the join users for each lession...
My job is to extend, on the gym web site, the option to the user to join the lessions...
So i'm going to write a PHP web service using nusoap for interface the DBF files to the net and call the service from the web site.

My question is:
Is it possible this solution cause a conflict when both user, one from web site and the second receptionists are adding a member to a scheduled lession?
How to prevent 2 people write something at the same time on a DBF file?

What do you think?

thank you