SYS@sales 2013-07-16 23:30:21> select username,blocking_session,blocking_session_status from v$session where blocking_session_status='VALID';
USERNAME BLOCKING_SESSION BLOCKING_SE
------------------------------ ---------------- -----------
SCOTT 97 VALID
USERNAME BLOCKING_SESSION BLOCKING_SE
------------------------------ ---------------- -----------
SCOTT 97 VALID
SYS@sales 2013-07-16 23:30:21> select username,blocking_session,blocking_session_status from v$session where blocking_session_status='VALID';
USERNAME BLOCKING_SESSION BLOCKING_SE
------------------------------ ---------------- -----------
SCOTT 97 VALID
SYS@sales 2013-07-16 23:42:01> select sid ,serial# from v$session where sid = 97;
SID SERIAL#
---------- ----------
97 16976
SYS@sales 2013-07-16 23:42:55> alter system kill session '97,16976';
System altered.