SELECT s.username, l.type,
decode(l.type, ' TM ', ' TABLE LOCK ',
' TX ', ' ROW LOCK ',
NULL) LOCK_LEVEL,
o.owner,o. object_name,o.object_type,
s.sid,s.serial#,s.terminal,s.machine,s.program,s.osuser,s.status
FROM v$session s,v$lock l,dba_objects o
WHERE l.sid = s.sid
AND l.id1 = o. object_id( +)
AND s.username is NOT NULL
and s.username = ' NC633 '
and decode(l.type, ' TM ', ' TABLE LOCK ',
' TX ', ' ROW LOCK ',
NULL) is not null
order by l.type;
select count( *) from v$session where status = ' ACTIVE '; -- 查詢oracle的並發連接數
select username, count(username) from v$session where username is not null group by username; -- 查看不同用戶的連接數
select * from all_users; -- 查看所有用戶：
-- 查看用戶或角色系統權限(直接賦值給用戶或角色的系統權限)：
select * from dba_sys_privs;
select * from user_sys_privs;
-- 查看角色(只能查看登陸用戶擁有的角色)所包含的權限
select * from role_sys_privs;
-- 查看用戶對象權限：
select * from dba_tab_privs;
select * from all_tab_privs;
select * from user_tab_privs;
-- 查看所有角色：
select * from dba_roles;
-- 查看用戶或角色所擁有的角色：
select * from dba_role_privs;
select * from user_role_privs;
-- 查看哪些用戶有sysdba或sysoper系統權限(查詢時需要相應權限)
select * from V$PWFILE_USERS;
select count( *) from v$process -- 當前的連接數
select value from v$parameter where name = ' processes ' -- 數據庫允許的最大連接數
alter system set processes = 300 scope = spfile;
重啟數據庫:
shutdown immediate;
startup;
-- 查看當前有哪些用戶正在使用數據
SELECT osuser, a.username,cpu_time /executions / 1000000 || ' s ', sql_fulltext,machine
from v$session a, v$sqlarea b
where a.sql_address =b.address order by cpu_time /executions desc;
select count( *) from v$session #連接數
select count( *) from v$session where status = ' ACTIVE ' #並發連接數
show parameter processes #最大連接
alter system set processes = value scope = spfile;重啟數據庫 #修改連接
SQL> Select count(*) from v$session where status='ACTIVE' ;
COUNT(*)
----------
20
SQL> Select count(*) from v$session;
COUNT(*)
----------
187
SQL> show parameter processes;
NAME TYPE VALUE
------------------------------------ ----------- ----------
aq_tm_processes integer 0
db_writer_processes integer 1
gcs_server_processes integer 0
job_queue_processes integer 10
log_archive_max_processes integer 2
processes integer 450
SQL>
並發指active,I SEE
SQL> select count(*) from v$session #連接數
SQL> Select count(*) from v$session where status='ACTIVE' #並發連接數
SQL> show parameter processes #最大連接
SQL> alter system set processes = value scope = spfile;重啟數據庫 #修改連接
unix 1個用戶session 對應一個操作系統 process
而 windows體現在線程
DBA要定時對數據庫的連接情況進行檢查，看與數據庫建立的會話數目是不是正常，如果建立了過多的連接，會消耗數據庫的資源。同時，對一些“掛死”的連接，可能會需要DBA手工進行清理。
以下的SQL語句列出當前數據庫建立的會話情況:
select sid,serial#,username,program,machine,status
from v$session;
輸出結果為:
SID SERIAL# USERNAME PROGRAM MACHINE STATUS
---- ------- ---------- ----------- --------------- --------
1 1 ORACLE.EXE WORK3 ACTIVE
2 1 ORACLE.EXE WORK3 ACTIVE
3 1 ORACLE.EXE WORK3 ACTIVE
4 1 ORACLE.EXE WORK3 ACTIVE
5 3 ORACLE.EXE WORK3 ACTIVE
6 1 ORACLE.EXE WORK3 ACTIVE
7 1 ORACLE.EXE WORK3 ACTIVE
8 27 SYS SQLPLUS.EXE WORKGROUP\\WORK3 ACTIVE
11 5 DBSNMP dbsnmp.exe WORKGROUP\\WORK3 INACTIVE
其中，
SID 會話(session)的ID號;
SERIAL# 會話的序列號，和SID一起用來唯一標識一個會話;
USERNAME 建立該會話的用戶名;
PROGRAM 這個會話是用什么工具連接到數據庫的;
STATUS 當前這個會話的狀態，ACTIVE表示會話正在執行某些任務，INACTIVE表示當前會話沒有執行任何操作;
如果DBA要手工斷開某個會話，則執行:
alter system kill session \'SID,SERIAL#\'
SELECT username, machine, program, status, COUNT (machine) AS
連接數量
FROM v$session
GROUP BY username, machine, program, status
ORDER BY machine;
顯示結果（每個人的機器上會不同）
SCHNEIDER|WORKGROUD\WANGZHENG|TOAD.exe|ACTIVE|1
SCHNEIDER|WORKGROUP\597728AA514F49D|sqlplusw.exe|INACTIVE|1
|WWW-Q6ZMR2OIU9V|ORACLE.EXE|ACTIVE|8
PUBLIC|||INACTIVE|0
as
select * from informationlaw as of TIMESTAMP to_timestamp('20121126 103435','yyyymmdd hh24miss');