This question is an exact duplicate of:
How can I get logon events from audit table for Feb, June, Oct and Dec?
I tried the query below, but it retrieves a lot of duplicate rows although I am using the distinct keyword in the query. Also this query takes long time.
select distinct os_username ,username, userhost, terminal, timestamp, action_name, logoff_time from dba_audit_session where timestamp between '01-FEB-2017' and '28-FEB-2017' order by timestamp;