oracle的用户session

SQL> drop  user user_test cascade;

drop user user_test cascade
*
ERROR at line 1:
ORA-01940: cannot drop a user that iscurrently connected

SQL> select username,sid,serial#,status from v$session where username='USER_TEST';

USERNAME   SID  SERIAL#  STATUS
---------- ---- ------- --------
USER_TEST  136  15565    INACTIVE

SQL> alter system kill session '136,15565';

System altered.

SQL> drop  user user_test cascade;

User dropped.