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

  当我们删除某个用户与用户所有对象时，如果用户正当前有连接数据库，则会报错：

SQL> conn /as sysdba
Connected.

SQL> drop user fc cascade;
drop user fc cascade
*
ERROR at line 1:
ORA-01940: cannot drop a user that is currently connected.

   通过v$session视图查出要删除的用户当前session信息，然后kill掉该用户session连接：

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

---------- ----------

      150      9019
SQL> alter system kill session '150,9019';
System altered.

    再执行dropuser操作便可成功：

SQL>  drop user fc cascade;
User dropped.