Oracle下session的查询与删除 1、查询当前session SQLgt; select username,sid,serial# from v$session where username is not

Oracle下session的查询与删除

SQL> select username,sid,serial# from v$session where username is not null;

USERNAME SID SERIAL#
------------------------------ ---------- ----------
SYS 144 4
HYL 146 48
SCOTT 147
HR 159 15
--SERIAL#:SID有可能会重复，，当两个session的SID重复时，SERIAL#用来区别session 2、删除当前session

SQL> alter system kill session '146,48';
System altered.

hyl的session下执行操作如下：

SQL> show user
USER is "HYL"
SQL> select * from test1;
select * from test1
*
ERROR at line 1:
ORA-00028: your session has been killed

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思路：先关闭session，然后再删除用户

演示：在不关闭session的情况下删除用户现象：
SQL> select username,account_status from dba_users;
--查看当前有哪些用户
USERNAME ACCOUNT_STATUS
------------------------------ --------------------------------
CSMIG OPEN
MGMT_VIEW OPEN
SYS OPEN
SYSTEM OPEN
HYL OPEN
OE EXPIRED & LOCKED
6 rows selected.

SQL> select username,sid,serial# from v$session where username is not null;
--通过v$session视图，查看会话的sid、serial#
USERNAME SID SERIAL#
------------------------------ ---------- ----------
SYS 144 4
HYL 146 54
SCOTT 147
HR 159 15

SQL> drop user hyl; --删除，报错了，表明会话中存在的用户是不能被删除的，需要先将其关闭
drop user hyl
*
ERROR at line 1:
ORA-01940: cannot drop a user that is currently connected

SQL> alter system kill session '146,54';
System altered.

User dropped.

--尝试hyl连接，报错，无法使用hyl登陆session
SQL> conn hyl/oracle
ERROR:
ORA-01017: invalid username/password; logon denied

Warning: You are no longer connected to ORACLE.

--查看dba_users数据字典，表明hyl用户已经被删除
SQL> select username,account_status from dba_users;

USERNAME ACCOUNT_STATUS
------------------------------ --------------------------------
CSMIG OPEN
MGMT_VIEW OPEN
SYS OPEN
SYSTEM OPEN
OE EXPIRED & LOCKED
5 rows selected.

小结：

查询当前会话：select username,sid,serial# from v$session where username is not null;
删除当前会话：alter system kill session 'sid，serial#';
删除当前会话的用户，先kill session，再drop user（若用户下有对象，使用cascade命令）

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