This single script provides the overall picture of the database in terms of Waits events, Active/Inactive killed sessions, Top Processes (physical I/O, logical I/O, memory and CPU processes), Top CPU usage by users, etc.

[code]set serveroutput on
declare
cursor c1 is select version
from v$instance;
cursor c2 is
select
host_name
, instance_name
, to_char(sysdate, 'HH24:MI:SS DD-MON-YY') currtime
, to_char(startup_time, 'HH24:MI:SS DD-MON-YY') starttime
from v$instance;
cursor c4 is
select * from (SELECT count(*) cnt, substr(event,1,50)