SQL & PL/SQL

Dear All

I have Trigger And I need Insert Terminal Name (Client) of Who Insert or update or delete on table.

How i can use it.

select terminal
into v_terminal_name
from v$session
where audsid = userenv('SESSIONID');

when use this pl/sql in the Trigger the error occured of v$session

PL/SQL: ORA-00942: table or view does not exist


Thanks In Advance