ORA-01940 oracle 无法删除用户

在drop user的报ora-01940，代码如下

SQL> drop user joey cascade;

drop user joey cascade
*
ERROR at line 1:

ORA-01940: cannot drop a user that is currently connected

解决方案

1：查询正在连接的会话

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


       SID    SERIAL#
---------- ----------
        31         41

2：杀死会话

SQL> alter system kill session '31,41';


System altered.

3：删除用户

SQL> drop user joey cascade;


User dropped.