select tablespace_name, file_id, file_name,
  round(bytes/(1024*1024),0) total_space   from dba_data_files  order by tablespace_name;
3、查看回滚段名称及大小
select segment_name, tablespace_name, r.status, (initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent, max_extents, v.curext CurExtent From dba_rollback_segs r, v$rollstat v
Where r.segment_id = v.usn(+) order by segment_name ;
4、查看控制文件
select name from v$controlfile;
5、查看日志文件
select member from v$logfile;
6、查看表空间的使用情况
select sum(bytes)/(1024*1024) as free_space,tablespace_name
from dba_free_space  group by tablespace_name;

SELECT A.TABLESPACE_NAME,A.BYTES TOTAL,B.BYTES USED, C.BYTES FREE,
(B.BYTES*100)/A.BYTES "% USED",(C.BYTES*100)/A.BYTES "% FREE"
FROM SYS.SM$TS_AVAIL A,SYS.SM$TS_USED B,SYS.SM$TS_FREE C
WHERE A.TABLESPACE_NAME=B.TABLESPACE_NAME AND A.TABLESPACE_NAME=C.TABLESPACE_NAME;

7、查看数据库库对象
select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;

8、查看数据库的版本　
Select version FROM Product_component_version
Where SUBSTR(PRODUCT,1,6)='Oracle';
9、查看数据库的创建日期和归档方式
Select Created, Log_Mode, Log_Mode From V$Database;
10、捕捉运行很久的SQL
select username,sid,opname, round(sofar*100 / totalwork,0) || '%' as progress,
time_remaining,sql_text from v$session_longops , v$sql where time_remaining <> 0
and sql_address = address and sql_hash_value = hash_value
/
11、查看数据表的参数信息
SELECT partition_name, high_value, high_value_length, tablespace_name,
pct_free, pct_used, ini_trans, max_trans, initial_extent,
next_extent, min_extent, max_extent, pct_increase, FREELISTS,
freelist_groups, LOGGING, BUFFER_POOL, num_rows, blocks,
empty_blocks, avg_space, chain_cnt, avg_row_len, sample_size,
last_analyzed  FROM dba_tab_partitions

--WHERE table_name = :tname AND table_owner = :towner
ORDER BY partition_position
12、查看还没提交的事务
select * from v$locked_object;
select * from v$transaction;
13、查找object为哪些进程所用
select p.spid, s.sid, s.serial# serial_num, s.username user_name, a.type object_type,
s.osuser os_user_name, a.owner, a.object object_name, decode(sign(48 - command),
1, to_char(command), 'Action Code #' || to_char(command) ) action, p.program oracle_process,
s.terminal terminal, s.program program, s.status session_status from v$session s, v$access a, v$process p
where s.paddr = p.addr and s.type = 'USER' and a.sid = s.sid and a.object='SUBSCRIBER_ATTR'
order by s.username, s.osuser
14、回滚段查看
select rownum, sys.dba_rollback_segs.segment_name Name, v$rollstat.extents
Extents, v$rollstat.rssize Size_in_Bytes, v$rollstat.xacts XActs,
v$rollstat.gets Gets, v$rollstat.waits Waits, v$rollstat.writes Writes,
sys.dba_rollback_segs.status status from v$rollstat, sys.dba_rollback_segs,
v$rollname where v$rollname.name(+) = sys.dba_rollback_segs.segment_name and
v$rollstat.usn (+) = v$rollname.usn order by rownum
15、耗资源的进程（top session）
select s.schemaname schema_name, decode(sign(48 - command), 1,
to_char(command), 'Action Code #' || to_char(command) ) action, status
session_status, s.osuser os_user_name, s.sid, p.spid , s.serial# serial_num,
nvl(s.username, '[Oracle process]') user_name, s.terminal terminal,
s.program program, st.value criteria_value from v$sesstat st, v$session s , v$process p
where st.sid = s.sid and st.statistic# = to_number('38') and ('ALL' = 'ALL'
or s.status = 'ALL') and p.addr = s.paddr order by st.value desc, p.spid asc, s.username asc, s.osuser asc
16、查看锁（lock）情况
select A.OWNER,A.OBJECT_NAME,B.XIDUSN,B.XIDSLOT,B.XIDSQN,
     B.SESSION_ID,B.ORACLE_USERNAME,B.OS_USER_NAME,B.PROCESS,
     B.LOCKED_MODE,C.MACHINE,C.STATUS,C.SERVER,C.SID,C.SERIAL#,
     C.PROGRAM from  ALL_OBJECTS A,V$LOCKED_OBJECT B,SYS.GV_$SESSION C
     WHERE ( A.OBJECT_ID = B.OBJECT_ID ) AND (B.PROCESS = C.PROCESS ) ;

alter system kill session 'sid,serial#' ;

17: 對臨時使用的表操作

對臨時使用的表操作可以如下，可以提高性能

Insert /*+ append */ into bmt_public_tmp Select * from bmt_public_tmp where 1=0

delete from bmt_public_tmp nologing where sid=123;

18、在存储过程里执行一个INSERT 语句，判断这个INSERT语句是否成功

If Sql%RowCount()>=1 Then

--INSERT成功

If Sql%RowCount()=0 Then

--INSERT  沒有成功

19、恢復誤刪除數據

SQL> select dbms_flashback.get_system_change_number from dual;

GET_SYSTEM_CHANGE_NUMBER

------------------------

               117733502

SQL> insert into wot_bom_attach  select * from wot_bom_attach  AS OF SCN 117700000 where stkno='BC16302TEST' and seq='0007';

20、查看V$SQLAREA
SELECT SQL_TEXT, SHARABLE_MEM, PERSISTENT_MEM, RUNTIME_MEM, SORTS,
VERSION_COUNT, LOADED_VERSIONS, OPEN_VERSIONS, USERS_OPENING, EXECUTIONS,
USERS_EXECUTING, LOADS, FIRST_LOAD_TIME, INVALIDATIONS, PARSE_CALLS, DISK_READS,
BUFFER_GETS, ROWS_PROCESSED FROM V$SQLAREA
21、有关connection的相关信息
1）查看有哪些用户连接
select s.osuser os_user_name, decode(sign(48 - command), 1, to_char(command),
'Action Code #' || to_char(command) ) action, p.program oracle_process,
status session_status, s.terminal terminal, s.program program,
s.username user_name, s.fixed_table_sequence activity_meter, '' query,
0 memory, 0 max_memory, 0 cpu_usage, s.sid, s.serial# serial_num
from v$session s, v$process p where s.paddr=p.addr and s.type = 'USER'
order by s.username, s.osuser
2）根据v.sid查看对应连接的资源占用等情况
select n.name,v.value, n.class, n.statistic# from v$statname n, v$sesstat v
where v.sid = 71 and v.statistic# = n.statistic# order by n.class, n.statistic#
3）根据sid查看对应连接正在运行的sql
select /*+ PUSH_SUBQ */ command_type, sql_text, sharable_mem, persistent_mem, runtime_mem, sorts,
version_count, loaded_versions, open_versions, users_opening, executions, users_executing, loads,
first_load_time, invalidations, parse_calls, disk_reads, buffer_gets, rows_processed, sysdate start_time,
sysdate finish_time, '>' || address sql_address, 'N' status from v$sqlarea
where address = (select sql_address from v$session where sid = 71)