一上执行过程，确实删除成功了

Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing optionsSQL> DROP USER c##xyt CASCADE;
DROP USER c##xyt CASCADE
*
第 1 行出现错误:
ORA-01940: 无法删除当前连接的用户SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'c##xyt';未选定行SQL> ALTER USER C##XYT account LOCK;用户已更改。SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'c##xyt';未选定行SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'C##XYT';SADDR                   SID    SERIAL# PADDR
---------------- ---------- ---------- ----------------
USERNAME                       STATUS
------------------------------ --------
00007FF838443EA0          3      36748 00007FF8352B70C0
C##XYT                         INACTIVE00007FF83643B740        185      50332 00007FF8373A4D08
C##XYT                         INACTIVE00007FF83850AD70        395      15275 00007FF8384087D0
C##XYT                         INACTIVESQL> alter system kill session '3,36748';系统已更改。SQL> alter system kill session '185,50332';系统已更改。SQL> alter system kill session '395,15275';系统已更改。SQL> DROP USER C##XYT CASCADE;用户已删除。SQL>

二步骤解析

2.1 锁定账户

将要删除的用户给锁定掉

SQL> ALTER USER C##XYT account LOCK;用户已更改。

2.2 查询待连接用户的进程号

SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'C##XYT';

正常来说都会有进程的，没有可能是因为

2.3 根据进程号kill掉进程

SQL> alter system kill session '3,36748';系统已更改。SQL> alter system kill session '185,50332';系统已更改。SQL> alter system kill session '395,15275';系统已更改。

2.4 级联删除掉用户

SQL> DROP USER C##XYT CASCADE;用户已删除。

三注意事项

oracle似乎要考虑大小写，比方说，我上头第一次查进程号时，查不到

SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'c##xyt';未选定行SQL> select saddr,sid,serial#,paddr,username,status from v$session where username = 'C##XYT';SADDR                   SID    SERIAL# PADDR
---------------- ---------- ---------- ----------------
USERNAME                       STATUS
------------------------------ --------
00007FF838443EA0          3      36748 00007FF8352B70C0
C##XYT                         INACTIVE00007FF83643B740        185      50332 00007FF8373A4D08
C##XYT                         INACTIVE00007FF83850AD70        395      15275 00007FF8384087D0
C##XYT                         INACTIVE