Unable to drop the undo tablespace

Question

Hi,
ORACLE VERSION:11.1.0
OPERATING SYSTEM :WINDOWS XP
I was uable to drop the undo tablespace .Here i create an new undo tablespace and trying to drop the old undo tablespace.
I had given alter system set UNDO_TABLESPACE=newundo tablespace.
And trying to drop the old one and getting the error like this
SQL> create undo tablespace undotbs02 datafile 'F:\APP\POORNAPRASADS\ORADATA\ORCL\UNDOTBS02.dbf' size 200m;
Tablespace created.
SQL> sho parameter undo
NAME                                 TYPE        VALUE
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS1
SQL> alter system set undo_tablespace=undotbs02;
System altered.
SQL> sho parameter undo
NAME                                 TYPE        VALUE
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS02
SQL> drop tablespace undotbs1 including contents and datafiles;
drop tablespace undotbs1 including contents and datafiles
ERROR at line 1:
ORA-30013: undo tablespace 'UNDOTBS1' is currently in use
SQL> drop tablespace undotbs1 including contents and datafiles;
drop tablespace undotbs1 including contents and datafiles
ERROR at line 1:
ORA-30013: undo tablespace 'UNDOTBS1' is currently in use

Answer 1

SELECT TO_CHAR (s.SID) || ',' || TO_CHAR (s.serial#) sid_serial,
NVL (s.username, 'None') orauser, s.program, r.NAME undoseg,
t.used_ublk * TO_NUMBER (x.VALUE) / 1024 || 'K' "Undo",
t1.tablespace_name
FROM SYS.v_$rollname r,
SYS.v_$session s,
SYS.v_$transaction t,
SYS.v_$parameter x,
dba_rollback_segs t1
WHERE s.taddr = t.addr
AND r.usn = t.xidusn(+)
AND x.NAME = 'db_block_size'
AND t1.segment_id = r.usn
AND t1.tablespace_name = 'UNDOTBS1'
Hth
Girish Sharma