(1)查看用户的连接状况

select username,sid,serial# from v$session

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如下结果：

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username????????? sid??????????????? serial#

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NETBNEW????????? 513????????????? 22974
NETBNEW???????? ?514????????????? 18183
NETBNEW????????? 516????????????? 21573
NETBNEW????????? 531????????????? 9
WUZHQ???????????? 532????????????? 4562

(2)找到要删除用户的sid,和serial，并删除

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如：你要删除用户'WUZHQ',可以这样做：

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alter system kill session'532,4562'

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(3)删除用户

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drop user username cascade

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(**)如果在drop 后还提示ORA-01940:无法删除当前已链接的用户，说明还有连接的session，可以通过查看session的状态来确定该session是否被kill 了，用如下语句查看：

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select saddr,sid,serial#,paddr,username,status from v$session where username is not null

结果如下(以我的库为例)：

?saddr???????????????????? sid????????? ?serial#??????????? paddr????????????? username????????????? status

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564A1E28????????????? 513?????????? 22974??????????? 569638F4?????? ?NETBNEW???????????? ACTIVE
564A30DC????????????? 514????????? 18183????????????569688CC??????? NETBNEW?????????? ?INACTIVE
564A5644???????????? ?516?????????? 21573??????????? 56963340?????? ?NETBNEW??????????? INACTIVE
564B6ED0????????????? 531???????? ? 9?????????????????? 56962D8C??????? NETBNEW??????????? INACTIVE
564B8184????????????? 532????????? 4562???????????????56A1075C??????? WUZHQ??????????????? KILLED

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status 为要删除用户的session状态，如果还为inactive，说明没有被kill掉，如果状态为killed，说明已kill。

由此可见，WUZHQ这个用户的session已经被杀死。此时可以安全删除用户。

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