I have three main objects. Appointments, Users, and Salons. There are many Users and many Salons. Users create Appointments to Salons. I have a form Users will use to create Appointments. I need to create a page rule for that form as follows: If count of Appointments to Salon(x) is >10 for Logged-in User, then page rule creates warning message.
How do I count how many appointments have been made a a specific Salon by user?