oracle 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 返回行的物理地址 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進程？ 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進程的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. 如何尋找重複記錄？ 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. 如何重複資料刪除記錄？ 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. 如何快速編譯所有視圖？ 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. 事務要求的復原段空間不夠，表現為資料表空間用滿（ORA-01560錯誤），復原段擴充到達參數 MAXEXTENTS的值（ORA-01628）的解決辦法. 向復原段資料表空間添加檔案或使已有的檔案變大；增加MAXEXTENTS的值。 144. 如何加密ORACLE的預存程序？ 下列預存程序內容放在AA.SQL檔案中 create or replace procedure testCCB(i in number) as begin dbms_output.put_line('輸入參數是'||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 (c) Oracle Corporation 1993, 2000. All Rights Reserved. Processing AA.sql to AA.plb 運行AA.plb SQL> @AA.plb ; 145. 如何監控案例的等待？ select event,sum(decode(wait_Time,0,0,1)) "Prev", sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot" from v$session_Wait group by event order by 4; 146. 如何復原段的爭用情況？ select name, waits, gets, waits/gets "Ratio" from v$rollstat C, v$rollname D where C.usn = D.usn; 147. 如何監控資料表空間的 I/O 比例？ select B.tablespace_name name,B.file_name "file",A.phyrds pyr, A.phyblkrd pbr,A.phywrts pyw, A.phyblkwrt pbw from v$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 中共用快取區的命中率，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 中重做日誌緩衝區的命中率，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運行什麼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$dispatcher; 此值大於0.5時，參數需加大 select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type='dispatcher'; select count(*) from v$dispatcher; select servers_highwater from v$mts; servers_highwater接近mts_max_servers時，參數需加大 159. 如何知道目前使用者的ID號? SQL>SHOW USER; OR SQL>select user from dual; 160. 如何查看片段程度高的表? 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. 如何知道表在資料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. 如何知道索引在資料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. 如何知道監聽器記錄檔? 以8I為例 $ORACLE_HOME/NETWORK/LOG/LISTENER.LOG 166. 如何知道監聽器參數檔案? 以8I為例 $ORACLE_HOME/NETWORK/ADMIN/LISTENER.ORA 167. 如何知道TNS 串連檔案? 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. 如何知道警告記錄檔? 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視圖? 以8I為例 $ORACLE_HOME/RDBMS/ADMIN/CATALOG.SQL 172. 如何知道建立審計用資料字典視圖? 以8I為例 $ORACLE_HOME/RDBMS/ADMIN/CATAUDIT.SQL 173. 如何知道建立快照用資料字典視圖? 以8I為例 $ORACLE_HOME/RDBMS/ADMIN/CATSNAP.SQL
