You could add a timestamp to the login table. You add a timer in the application that will update the timestamp at a given intervall (let say int).

When you count the total number of users log in the system, ignore records that have a timestamp < current datetime - int.

HTH

>In my app I have a login procedure and everytime someone login I update my login table and this tell me how many users are login and I also have a logout procedure that update the login table, this will work well in a perfect world, where I see a problem is if the users computer shutdown prematurely, if this happen it would not update my login table, so the login count would be off.
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>I need some ideals on how many users are login to the application.