select sql_text, executions from v$sql where cpu_time > 20000;

select * from v$session where machine = ‘xxxx’ and logon_time > sysdate - 1;

select sid, ctime from v$lock where block > 0;

select
oracle_username
os_user_name,
locked_mode,
object_name,
object_type
from
v$locked_object a,dba_objects b
where
a.object_id = b.object_id

select s.sid, p.spid, s.status,s.process,s.osuser, a.sql_text, p.program
from
v$session s, v$sqlarea a, v$process p
where
s.sql_hash_value=a.hash_value
and s.sql_address=a.address
and s.paddr=p.addr
and s.status='ACTIVE';


The views are owned by the SYS user. You can query $V$FIXED_TABLE to see all the view names. Read consistency is not guaranteed.

More complicated example:
Oracle Session I/O
New Performance Views to Identify Problem SQL

SELECT
TO_CHAR(logon_time,'DD-MON-YY HH:MI:SS PM') LOGON_TIME,
(sum(DECODE(c.NAME,'physical reads',VALUE,0)) +
sum(DECODE(c.NAME,'physical writes',VALUE,0)) +
sum(DECODE(c.NAME,'physical writes direct',VALUE,0)) +
sum(DECODE(c.NAME,'physical writes direct (lob)',VALUE,0))+
sum(DECODE(c.NAME,'physical reads direct (lob)',VALUE,0)) +
sum(DECODE(c.NAME,'physical reads direct',VALUE,0)))
total_physical_io,
(sum(DECODE(c.NAME,'db block gets',VALUE,0)) +
sum(DECODE(c.NAME,'db block changes',VALUE,0)) +
sum(DECODE(c.NAME,'consistent changes',VALUE,0)) +
sum(DECODE(c.NAME,'consistent gets',VALUE,0)) )
total_logical_io,
(sum(DECODE(c.NAME,'session pga memory',VALUE,0))+
sum(DECODE(c.NAME,'session uga memory',VALUE,0)) )
total_memory_usage,
sum(DECODE(c.NAME,'parse count (total)',VALUE,0)) parses,
sum(DECODE(c.NAME,'CPU used by this session',VALUE,0))
total_cpu,
sum(DECODE(c.NAME,'parse time cpu',VALUE,0)) parse_cpu,
sum(DECODE(c.NAME,'recursive cpu usage',VALUE,0))
recursive_cpu,
sum(DECODE(c.NAME,'CPU used by this session',VALUE,0)) -
sum(DECODE(c.NAME,'parse time cpu',VALUE,0)) -
sum(DECODE(c.NAME,'recursive cpu usage',VALUE,0))
other_cpu,
sum(DECODE(c.NAME,'sorts (disk)',VALUE,0)) disk_sorts,
sum(DECODE(c.NAME,'sorts (memory)',VALUE,0)) memory_sorts,
sum(DECODE(c.NAME,'sorts (rows)',VALUE,0)) rows_sorted,
sum(DECODE(c.NAME,'user commits',VALUE,0)) commits,
sum(DECODE(c.NAME,'user rollbacks',VALUE,0)) rollbacks,
sum(DECODE(c.NAME,'execute count',VALUE,0)) executions
FROM sys.V_$SESSTAT a,
sys.V_$SESSION b,
sys.V_$STATNAME c,
sys.v_$process d,
sys.v_$bgprocess e