■查看哪些session正在使用哪些回滾段?
測試方法： 打開多個SQL*Plus窗口，一些做一些需要回滾的操作，如insert，delete等，一個執行以下的語句來監視。?

col "回滾段名" format a10
col SID format 9990
col "用戶名" format a10
col "操作程序" format a80
col status format a6 trunc

SELECT r.name "回滾段名",
s.sid,
s.serial#,
s.username "用戶名",
t.status,
t.cr_get,
t.phy_io,
t.used_ublk,
t.noundo,
substr(s.program, 1, 78) "操作程序"
FROM sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r
WHERE t.addr = s.taddr and t.xidusn = r.usn
ORDER BY t.cr_get,t.phy_io
/

■查詢數據庫中有效的字符集
SQL> col nls_charset_id for 9999
SQL> col nls_charset_name for a30
SQL> col hex_id for a20
SQL> select
nls_charset_id(value) nls_charset_id,
value nls_charset_name,
to_char(nls_charset_id(value),'xxxx') hex_id
from? v$nls_valid_values
where parameter = 'CHARACTERSET'
order by nls_charset_id(value);

■查看oracle實例
SQL> select instance_name from v$instance;

■修改塊跟蹤文件
SQL> alter database enable block change tracking
? 2? using file
? 3? '/export/home/opt/product/10.2.0.1.0/admin/orcl/changed_blocks.bct';

Database altered.
? 禁用塊跟蹤文件
SQL> alter database disable block change tracking;

■創建表空間??
CREATE SMALLFILE TABLESPACE "YUHJ_SPACE"?
DATAFILE '/export/home/opt/product/oradata/orcl/yuhj_datafile'?
SIZE 10M AUTOEXTEND ON NEXT 50K MAXSIZE 20M?
LOGGING EXTENT MANAGEMENT LOCAL SEGMENT SPACE MANAGEMENT AUTO

■創建臨時表空間??
CREATE SMALLFILE TEMPORARY TABLESPACE "YHJ_TEMP_SPACE"?
TEMPFILE '/export/home/opt/product/oradata/orcl/yhj_tempfile' SIZE 5M?
AUTOEXTEND ON NEXT 56K MAXSIZE 10M EXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M

■創建數據文件??
ALTER TABLESPACE "YUHJ_SPACE"?
ADD DATAFILE '/export/home/opt/product/oradata/orcl/yhj_datafile' SIZE 2M?
AUTOEXTEND ON NEXT 56K MAXSIZE UNLIMITED/15M

■創建回滾段??
CREATE ROLLBACK SEGMENT "SYSTEM"?
TABLESPACE "SYSTEM"?
STORAGE (INITIAL 112K MINEXTENTS 1 MAXEXTENTS 32765 )

■改變回滾段狀態(上線/離線)
ALTER ROLLBACK SEGMENT "SYSTEM" ONLINE/OFFLINE

■創建重做日志組
ALTER DATABASE ADD?
LOGFILE GROUP 4 ( '/export/home/opt/product/oradata/orcl/redo4.log') SIZE 51200K

■設定SGA總大小
ALTER SYSTEM SET sga_target = 209715200 SCOPE=BOTH

■設定SGA最大在小
ALTER SYSTEM SET sga_max_size = 262144000 COMMENT='internally adjusted' SCOPE=SPFILE

說明:
?? "SGA 最大大小"指定數據庫可以分配的最大內存.如果指定了"SGA 最大大小", 則以后可以動態
?? 更改上述 SGA 總大小 (提供的 SGA 總大小不能超過 SGA 最大大小).

■設定PGA內存分配
ALTER SYSTEM SET pga_aggregate_target = 25769803776 SCOPE=BOTH

■改變會話日期格式
? ALTER SESSION SET NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';
?
? 改變會話時區
? ALTER SESSION SET TIME_ZONE = '-05:00';

? 改變數據庫的時區
? ALTER DATABASE SET TIME_ZONE = '-05:00';

■查詢觸發器
? select * from user_triggers;
? select * from all_triggers;
? select * from dba_triggers;

■查詢當前用戶在emp表上創建的所有觸發器
? SQL> select trigger_name, status from user_triggers where table_name = 'EMP';

■禁止觸發器
? SQL> alter trigger tr_emp_time DISABLE;

■激活觸發器
? SQL> alter trigger tr_emp_time ENABLE;

■激活或禁止表上的所有觸發器
? SQL> alter table dept DISABLE ALL TRIGGERS;
? SQL> alter table emp ENABLE ALL TRIGGERS;

■重新編譯觸發器
? SQL> alter trigger tr_emp_time compile;

■刪除觸發器
? SQL> drop trigger tr_emp_time;