By Querying the AD_Session
Table, you can get the no of users logged into the system.
You will get active/inactive connections based on the processed
column.
For getting active users in the system :-
SELECT AD_Org_ID, AD_Role_ID, remote_addr, remote_host, processed, logindate,
created as "login date with time", createdby As AD_User_ID FROM AD_Session
WHERE Processed='N' AND logindate > current_date-1;
(you can update the above sql as your wish)