Used to delete a user that is considered offline when the number of online users is displayed.

Number of online users in the status bar!
Idea: use the process of refreshing messages in real time to calculate the number of online users from the database table. If you have stayed for more than 20 minutes, you will be taken offline.
Table used: upline
Create table online -- used to display online users
(User_id number,
OperateTiem date
)

Used to delete offline users

Create or replace procedure DelOnLine is
Cursor c_upline is select * from upline;
Ss number;
Begin
For man in c_upline loop
Select (sysdate-man. operatetime) * 24*60*60 into ss from dual;
If ss> 60 then
Delete from upline where user_id = man. user_id;
End if;
End loop;
End DelOnLine;