Orace DBA scripts: wait event scripts

-- sessions with highest CPU consumption
SELECT s.sid, s.serial#, p.spid as "OS PID",s.username, s.module, st.value/100 as "CPU sec"
FROM v$sesstat st, v$statname sn, v$session s, v$process p
WHERE sn.name = 'CPU used by this session' -- CPU
AND st.statistic# = sn.statistic#
AND st.sid = s.sid
AND s.paddr = p.addr
AND s.last_call_et < 3600 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours

-- sessions with the highest time for a certain wait
SELECT s.sid, s.serial#, p.spid as "OS PID", s.username, s.module, se.time_waited
FROM v$session_event se, v$session s, v$process p
WHERE se.event = '&event_name'
AND s.last_call_et < 1800 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours
AND se.sid = s.sid
AND s.paddr = p.addr
ORDER BY se.time_waited;

-- sessions with highest DB Time usage
SELECT s.sid, s.serial#, p.spid as "OS PID", s.username, s.module, st.value/100 as "DB Time (sec)"
, stcpu.value/100 as "CPU Time (sec)", round(stcpu.value / st.value * 100,2) as "% CPU"
FROM v$sesstat st, v$statname sn, v$session s, v$sesstat stcpu, v$statname sncpu, v$process p
WHERE sn.name = 'DB time' -- CPU
AND st.statistic# = sn.statistic#
AND st.sid = s.sid
AND  sncpu.name = 'CPU used by this session' -- CPU
AND stcpu.statistic# = sncpu.statistic#
AND stcpu.sid = st.sid
AND s.paddr = p.addr
AND s.last_call_et < 1800 -- active within last 1/2 hour
AND s.logon_time > (SYSDATE - 240/1440) -- sessions logged on within 4 hours
AND st.value > 0

--session statistics for a particular session :
 select  s.sid,s.username,st.name,se.value
from v$session s, v$sesstat se, v$statname st
where s.sid=se.SID and se.STATISTIC#=st.STATISTIC#
--and st.name ='CPU used by this session'
and s.username='&USERNAME'
order by s.sid,se.value desc

If non DBA user want to see its own statistics then it should grants as below:
grant select on sys.V_$SESSION to username;
grant select on sys.V_$STATNAME to username;
grant select on sys.V_$MYSTAT to username;

and replace view v$sesstat by v$mystat

another useful grants :
grant select on sys.V_$PROCESS to username;
grant select on sys.DBA_2PC_PENDING to username;
grant select on sys.v_$SQLTEXT to username;
grant select on sys.v_$SQL to username;