Does anyone know how to accomplish this?

Display/show the total number of registered users along with updating it on a separate html and/or php page that isn't affiliated with oxwall pages BUT connects to the same database?

So for example, on this page, it would display the number of registered users and if another registers, it would add 1.  

<p>Over <php "echo" statement here that displays total number of users> have joined up already!</p>

php and pdo is preferred.