ORACLE常用傻瓜問題1000問(之四)(轉)

ORACLE常用傻瓜問題1000問(之四)(轉)[@more@]

大家在應用ORACLE的時候可能會遇到很多看起?聿渾y的問題, 特別對新手?碚f, 今天我簡單把它總結一下, 發布給大家, 希望對大家有幫助! 和大家一起探討, 共同進步!

對ORACLE高手?碚f是不用看的.

虛擬欄位

133. CURRVAL 和 nextval

為表建立序列

CREATE SEQUENCE EMPSEQ ... ;

SELECT empseq.currval FROM DUAL ;

自動插入序列的數值

INSERT INTO emp

VALUES (empseq.nextval, 'LEWIS', 'CLERK',

7902, SYSDATE, 1200, NULL, 20) ;

134. ROWNUM

按設定排序的行的序號

SELECT * FROM emp WHERE ROWNUM < 10 ;

135. ROWID

返回行的實體地址

SELECT ROWID, ename FROM emp WHERE deptno = 20 ;

136. 將N秒轉換為時分秒格式？

set serverout on

declare

N number := 1000000;

ret varchar2(100);

begin

ret := trunc(n/3600) || '小時' || to_char(to_date(mod(n,3600),'sssss'),'fmmi"分 "ss"秒"') ;

dbms_output.put_line(ret);

end;

137. 如何查詢做比較大的排序的程式？

SELECT b.tablespace, b.segfile#, b.segblk#, b.blocks, a.sid, a.serial#,

a.username, a.osuser, a.status

FROM v$session a,v$sort_usage b

WHERE a.saddr = b.session_addr

ORDER BY b.tablespace, b.segfile#, b.segblk#, b.blocks ;

138. 如何查詢做比較大的排序的程式的SQL語句？

select /*+ ORDERED */ sql_text from v$sqltext a

where a.hash_value = (

select sql_hash_value from v$session b

where b.sid = &sid and b.serial# = &serial)

order by piece asc ;

139. 如何查詢重複記錄？

SELECT * FROM TABLE_NAME

WHERE ROWID!=(SELECT MAX(ROWID) FROM TABLE_NAME D

WHERE TABLE_NAME.COL1=D.COL1 AND TABLE_NAME.COL2=D.COL2);

140. 如何刪除重複記錄？

DELETE FROM TABLE_NAME

WHERE ROWID!=(SELECT MAX(ROWID) FROM TABLE_NAME D

WHERE TABLE_NAME.COL1=D.COL1 AND TABLE_NAME.COL2=D.COL2);

141. 如何快速編譯所有檢視？

SQL >SPOOL VIEW1.SQL

SQL >SELECT ‘ALTER VIEW ‘||TNAME||’

COMPILE;’ FROM TAB;

SQL >SPOOL OFF

然後執行VIEW1.SQL即可。

SQL >@VIEW1.SQL;

142. ORA-01555 SNAPSHOT TOO OLD的解決辦法

增加MINEXTENTS的值，增加區的大小，設定一個高的OPTIMAL值。

143. 事務要求的回滾段空間不夠，表現為表空間用滿（ORA-01560錯誤），回滾段擴充套件到達引數 MAXEXTENTS的值（ORA-01628）的解決辦法.

向回滾段表空間新增檔案或使已有的檔案變大；增加MAXEXTENTS的值。

144. 如何加密ORACLE的儲存過程？

下列儲存過程內容放在AA.SQL檔案中

create or replace procedure testCCB(i in number) as

begin

dbms_output.put_line('輸入引數是'||to_char(i));

end;

SQL>wrap iname=a.sql;

PL/SQL Wrapper: Release 8.1.7.0.0 - Production on Tue Nov 27 22:26:48 2001

Copyright © Oracle Corporation 1993, 2000. All Rights Reserved.

Processing AA.sql to AA.plb

執行AA.plb

SQL> @AA.plb ;

145. 如何監控事例的等待？

select event,sum(decode(wait_Time,0,0,1)) "Prev",

sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot"

from v$session_Wait

group by event order by 4;

146. 如何回滾段的爭用情況？

select name, waits, gets, waits/gets "Ratio"

from v$rollstat C, v$rollname D

where C.usn = D.usn;

147. 如何監控表空間的 I/O 比例？

select B.tablespace_name name,B.file_name "file",A.phyrds pyr,

A.phyblkrd pbr,A.phywrts pyw, A.phyblkwrt pbw

from v$filestat A, dba_data_files B

where A.file# = B.file_id

order by B.tablespace_name;

148. 如何監控檔案系統的 I/O 比例？

select substr(C.file#,1,2) "#", substr(C.name,1,30) "Name",

C.status, C.bytes, D.phyrds, D.phywrts

from v$datafile C, v$filestat D

where C.file# = D.file#;

149. 如何在某個使用者下找所有的索引？

select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name

from user_ind_columns, user_indexes

where user_ind_columns.index_name = user_indexes.index_name

and user_ind_columns.table_name = user_indexes.table_name

order by user_indexes.table_type, user_indexes.table_name,

user_indexes.index_name, column_position;

150. 如何監控 SGA 的命中率？

select a.value + b.value "logical_reads", c.value "phys_reads",

round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT RATIO"

from v$sysstat a, v$sysstat b, v$sysstat c

where a.statistic# = 38 and b.statistic# = 39

and c.statistic# = 40;

151. 如何監控 SGA 中字典緩衝區的命中率？

select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",

(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"

from v$rowcache

where gets+getmisses <>0

group by parameter, gets, getmisses;

152. 如何監控 SGA 中共享快取區的命中率，應該小於1% ？

select sum(pins) "Total Pins", sum(reloads) "Total Reloads",

sum(reloads)/sum(pins) *100 libcache

from v$librarycache;

select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent"

from v$librarycache;

153. 如何顯示所有資料庫物件的類別和大小？

select count(name) num_instances ,type ,sum(source_size) source_size ,

sum(parsed_size) parsed_size ,sum(code_size) code_size ,sum(error_size) error_size,

sum(source_size) +sum(parsed_size) +sum(code_size) +sum(error_size) size_required

from dba_object_size

group by type order by 2;

154. 監控 SGA 中重做日誌快取區的命中率，應該小於1%

SELECT name, gets, misses, immediate_gets, immediate_misses,

Decode(gets,0,0,misses/gets*100) ratio1,

Decode(immediate_gets+immediate_misses,0,0,

immediate_misses/(immediate_gets+immediate_misses)*100) ratio2

FROM v$latch WHERE name IN ('redo allocation', 'redo copy');

155. 監控記憶體和硬碟的排序比率，最好使它小於 .10，增加 sort_area_size

SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts (disk)');

156. 如何監控當前資料庫誰在執行什麼SQL語句？

SELECT osuser, username, sql_text from v$session a, v$sqltext b

where a.sql_address =b.address order by address, piece;

157. 如何監控字典緩衝區？

SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM V$LIBRARYCACHE;

SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE" FROM V$ROWCACHE;

SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE EXECUTING" FROM V$LIBRARYCACHE;

後者除以前者,此比率小於1%,接近0%為好。

SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"

FROM V$ROWCACHE

158. 監控 MTS

select busy/(busy+idle) "shared servers busy" from v$dispatcher;

此值大於0.5時，引數需加大

select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type='dispatcher';

select count(*) from v$dispatcher;

select servers_highwater from v$mts;

servers_highwater接近mts_max_servers時，引數需加大

159. 如何知道當前使用者的ID號?

SQL>SHOW USER;

OR

SQL>select user from dual;

160. 如何檢視碎片程度高的表?

SELECT segment_name table_name , COUNT(*) extents

FROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY segment_name

HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);

162. 如何知道表在表空間中的儲存情況?

select segment_name,sum(bytes),count(*) ext_quan from dba_extents where

tablespace_name='&tablespace_name' and segment_type='TABLE' group by tablespace_name,segment_name;

163. 如何知道索引在表空間中的儲存情況?

select segment_name,count(*) from dba_extents where segment_type='INDEX' and owner='&owner'

group by segment_name;

164、如何知道使用CPU多的使用者session?

11是cpu used by this session

select a.sid,spid,status,substr(a.program,1,40) prog,a.terminal,osuser,value/60/100 value

from v$session a,v$process b,v$sesstat c

where c.statistic#=11 and c.sid=a.sid and a.paddr=b.addr order by value desc;

165. 如何知道監聽器日誌檔案?

以8I為例

$ORACLE_HOME/NETWORK/LOG/LISTENER.LOG

166. 如何知道監聽器引數檔案?

以8I為例

$ORACLE_HOME/NETWORK/ADMIN/LISTENER.ORA

167. 如何知道TNS 連線檔案?

以8I為例

$ORACLE_HOME/NETWORK/ADMIN/TNSNAMES.ORA

168. 如何知道Sql*Net 環境檔案?

以8I為例

$ORACLE_HOME/NETWORK/ADMIN/SQLNET.ORA

169. 如何知道警告日誌檔案?

以8I為例

$ORACLE_HOME/ADMIN/SID/BDUMP/SIDALRT.LOG

170. 如何知道基本結構?

以8I為例

$ORACLE_HOME/RDBMS/ADMIN/STANDARD.SQL

171. 如何知道建立資料字典檢視?

以8I為例

$ORACLE_HOME/RDBMS/ADMIN/CATALOG.SQL

172. 如何知道建立審計用資料字典檢視?

以8I為例

$ORACLE_HOME/RDBMS/ADMIN/CATAUDIT.SQL

173. 如何知道建立快照用資料字典檢視?

以8I為例

$ORACLE_HOME/RDBMS/ADMIN/CATSNAP.SQL

待續..