I'm asked to create an online booking system with online payment and I'm wondering what to do in the case when 2 customers booked for the same room(s) at the same time. For Example: At the same time: Customer1 and Customer2 booked for a standard room which only has 1 room available. (The Room availability will display that there is still 1 room available). And then they hit the 'confirm' button at the same time.