???? select ?t.tablespace_name,? round ( sum (bytes / ( 1024 * 1024 )), 0 )?ts_size
????
from ?dba_tablespaces?t,?dba_data_files?d
????
where ?t.tablespace_name? = ?d.tablespace_name
????
group ? by ?t.tablespace_name;

2、查看表空間物理文件的名稱及大小

?? select ?tablespace_name,? file_id ,? file_name ,
??
round (bytes / ( 1024 * 1024 ), 0 )?total_space
??
from ?dba_data_files
??
order ? by ?tablespace_name;

3、查看回滾段名稱及大小

?? 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、查看表空間的使用情況?

?? 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、查看數據庫庫對象?

select ?owner,?object_type,?status,? count ( * )? count #? from ?all_objects? group ? by ?owner,?object_type,?status;

8、查看數據庫的版本 ?

?? Select ?version? FROM ?Product_component_version
??
Where ?SUBSTR(PRODUCT, 1 , 6 ) = ' Oracle ' ;

9、查看數據庫的創建日期和歸檔方式?

?? Select ?Created,?Log_Mode,?Log_Mode? From ?V$ Database ;

?10、查看當前所有對象??

? select ? * ? from ?tab;

?11、建一個和a表結構一樣的空表??

? create ? table ?b? as ? select ? * ? from ?a? where ? 1 = 2 ;?
?
create ? table ?b(b1,b2,b3)? as ? select ?a1,a2,a3? from ?a? where ? 1 = 2;

?12、察看數據庫的大小,和空間使用情況??

????? ?col?tablespace?format?a20
?????
?select?b.file_id  --文件ID,
  b.tablespace_name  --表空間,
  b.file_name     --物理文件名,
  b.bytes       --總字節數,
  (b.bytes-sum(nvl(a.bytes,0)))   --已使用,
  sum(nvl(a.bytes,0))        --剩余,
  sum(nvl(a.bytes,0))/(b.bytes)*100 --剩余百分比
  from?dba_free_space?a,dba_data_files?b
  
where?a.file_id=b.file_id
  
group?by?b.tablespace_name,b.file_name,b.file_id,b.bytes
  
order?by?b.tablespace_name
  
/
  dba_free_space?
--表空間剩余空間狀況
  dba_data_files?--數據文件空間占用情況

13、查看現有回滾段及其狀態??

col?segment?format?a30
SELECT ?SEGMENT_NAME,OWNER,TABLESPACE_NAME,SEGMENT_ID, FILE_ID ,STATUS? FROM ?DBA_ROLLBACK_SEGS;

?14、查看數據文件放置的路徑??

?col? file_name ?format?a50
?
select ?tablespace_name, file_id ,bytes / 1024 / 1024 , file_name ? from ?dba_data_files? order ? by ? file_id ;

?15、顯示當前連接用戶??

show? user

?16、把SQL*Plus當計算器??

select ? 100 * 20 ? from ?dual;

?17、連接字符串??

? select ?列1 || 列2? from ?表1;
?
select ?concat(列1,列2)? from ?表1;

?18、查詢當前日期??

? select ?to_char(sysdate, ' yyyy-mm-dd,hh24:mi:ss ' )? from ?dual;

?19、用戶間復制數據??

?copy? from ?user1? to ?user2? create ?table2?using? select ? * ? from ?table1;

?20、視圖中不能使用order by,但可用group by代替來達到排序目的??

? create ? view ?a? as ? select ?b1,b2? from ?b? group ? by ?b1,b2;

?21、通過授權的方式來創建用戶??

? grant ?connect,resource? to ?test?identified? by ?test;?
?conn?test
/ test;