ORACLE常用傻瓜問題1000問(之四) (转)[&＃64;more&＃64;]
ORACLE常用傻瓜問題1000問(之四)XML:namespace prefix &＃61; o ns &＃61; "urn:schemas-microsoft-com:Office:office" />
作者: CCBZZP
大家在應用ORACLE的時候可能會遇到很多看起來不難的問題, 特別對新手來說, 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高手來說是不用看的.
虚擬字段
133. CURRVAL 和 nextval
为表创建序列
CREATE SEQUENCE EMPSEQ ... ;
select empseq.currval FROM DUAL ;
自动插入序列的数值
INSERT INTO emp
VALUES (empseq.nextval, &＃39;LEWIS&＃39;, &＃39;CLERK&＃39;,
7902, SYSDATE, 1200, NULL, 20) ;
134. ROWNUM
按设定排序的行的序号
SELECT * FROM emp WHERE ROWNUM <10 ;
135. ROWID
返回行的物理地址
SELECT ROWID, ename FROM emp WHERE deptno &＃61; 20 ;
136. 将N秒转换为时分秒格式&＃xff1f;
set serverout on
declare
N number :&＃61; 1000000;
ret varchar2(100);
begin
ret :&＃61; trunc(n/3600) || &＃39;小时&＃39; || to_char(to_date(mod(n,3600),&＃39;sssss&＃39;),&＃39;fmmi"分 "ss"秒"&＃39;) ;
dbms_output.put_line(ret);
end;
137. 如何查询做比较大的排序的进程&＃xff1f;
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 &＃61; b.session_addr
ORDER BY b.tablespace, b.segfile#, b.segblk#, b.blocks ;
138. 如何查询做比较大的排序的进程的sql语句&＃xff1f;
select /*&＃43; ORDERED */ sql_text from v$sqltext a
where a.hash_value &＃61; (
select sql_hash_value from v$session b
where b.sid &＃61; &sid and b.serial# &＃61; &serial)
order by piece asc ;
139. 如何查找重复记录&＃xff1f;
SELECT * FROM TABLE_NAME
WHERE ROWID!&＃61;(SELECT MAX(ROWID) FROM TABLE_NAME D
WHERE TABLE_NAME.COL1&＃61;D.COL1 AND TABLE_NAME.COL2&＃61;D.COL2);
140. 如何删除重复记录&＃xff1f;
DELETE FROM TABLE_NAME
WHERE ROWID!&＃61;(SELECT MAX(ROWID) FROM TABLE_NAME D
WHERE TABLE_NAME.COL1&＃61;D.COL1 AND TABLE_NAME.COL2&＃61;D.COL2);
141. 如何快速编译所有视图&＃xff1f;
SQL >SPOOL VIEW1.SQL
SQL >SELECT ‘ALTER VIEW ‘||TNAME||’
COMPILE;’ FROM TAB;
SQL >SPOOL OFF
然后执行VIEW1.SQL即可。
SQL >&＃64;VIEW1.SQL;
142. ORA-01555 SNAPSHOT TOO OLD的解决办法
增加MINEXTENTS的值&＃xff0c;增加区的大小&＃xff0c;设置一个高的OPTIMAL值。
143. 事务要求的回滚段空间不够&＃xff0c;表现为表空间用满&＃xff08;ORA-01560错误&＃xff09;&＃xff0c;回滚段扩展到达参数 MAXEXTENTS的值&＃xff08;ORA-01628&＃xff09;的解决办法.
向回滚段表空间添加文件或使已有的文件变大&＃xff1b;增加MAXEXTENTS的值。
144. 如何加密ORACLE的存储过程&＃xff1f;
下列存储过程内容放在AA.SQL文件中
create or replace procedure testCCB(i in number) as
begin
dbms_output.put_line(&＃39;输入参数是&＃39;||to_char(i));
end;
SQL>wrap iname&＃61;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
运行AA.plb
SQL> &＃64;AA.plb ;
145. 如何监控事例的等待&＃xff1f;
select event,sum(decode(wait_Time,0,0,1)) "Prev",
sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot"
from v$session_Wait
group by event order by 4;
146. 如何回滚段的争用情况&＃xff1f;
select name, waits, gets, waits/gets "Ratio"
from v$rollstat C, v$rollname D
where C.usn &＃61; D.usn;
147. 如何监控表空间的 I/O 比例&＃xff1f;
select B.tablespace_name name,B.file_name "file",A.phyrds pyr,
A.phyblkrd pbr,A.phywrts pyw, A.phyblkwrt pbw
from v$filestat A, dba_data_files B
where A.file# &＃61; B.file_id
order by B.tablespace_name;
148. 如何监控文件系统的 I/O 比例&＃xff1f;
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# &＃61; D.file#;
149. 如何在某个用户下找所有的索引&＃xff1f;
select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name
from user_ind_columns, user_indexes
where user_ind_columns.index_name &＃61; user_indexes.index_name
and user_ind_columns.table_name &＃61; user_indexes.table_name
order by user_indexes.table_type, user_indexes.table_name,
user_indexes.index_name, column_position;
150. 如何监控 SGA 的命中率&＃xff1f;
select a.value &＃43; b.value "logical_reads", c.value "phys_reads",
round(100 * ((a.value&＃43;b.value)-c.value) / (a.value&＃43;b.value)) "BUFFER HIT RATIO"
from v$sysstat a, v$sysstat b, v$sysstat c
where a.statistiC# &＃61; 38 and b.statistic# &＃61; 39
and c.statistic# &＃61; 40;
151. 如何监控 SGA 中字典缓冲区的命中率&＃xff1f;
select parameter, gets,Getmisses , getmisses/(gets&＃43;getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)&＃43;sum(getmisses))))*100 "Hit ratio"
from v$rowcache
where gets&＃43;getmisses <>0
group by parameter, gets, getmisses;
152. 如何监控 SGA 中共享缓存区的命中率&＃xff0c;应该小于1% &＃xff1f;
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. 如何显示所有数据库对象的类别和大小&＃xff1f;
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) &＃43;sum(parsed_size) &＃43;sum(code_size) &＃43;sum(error_size) size_required
from dba_object_size
group by type order by 2;
154. 监控 SGA 中重做日志缓存区的命中率&＃xff0c;应该小于1%
SELECT name, gets, misses, immediate_gets, immediate_misses,
Decode(gets,0,0,misses/gets*100) ratio1,
Decode(immediate_gets&＃43;immediate_misses,0,0,
immediate_misses/(immediate_gets&＃43;immediate_misses)*100) ratio2
FROM v$latch WHERE name IN (&＃39;redo allocation&＃39;, &＃39;redo copy&＃39;);
155. 监控内存和硬盘的排序比率&＃xff0c;最好使它小于 .10&＃xff0c;增加 sort_area_size
SELECT name, value FROM v$sysstat WHERE name IN (&＃39;sorts (memory)&＃39;, &＃39;sorts (disk)&＃39;);
156. 如何监控当前数据库谁在运行什么SQL语句&＃xff1f;
SELECT osuser, username, sql_text from v$session a, v$sqltext b
where a.sql_address &＃61;b.address order by address, piece;
157. 如何监控字典缓冲区&＃xff1f;
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$LIBRARYCACHE;
后者除以前者,此比率小于1%,接近0%为好。
SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
FROM V$ROWCACHE
158. 监控 MTS
select busy/(busy&＃43;idle) "shared servers busy" from v$dispatcher;
此值大于0.5时&＃xff0c;参数需加大
select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type&＃61;&＃39;dispatcher&＃39;;
select count(*) from v$dispatcher;
select servers_highwater from v$mts;
servers_highwater接近mts_max_servers时&＃xff0c;参数需加大
159. 如何知道当前用户的ID号?
SQL>SHOW USER;
OR
SQL>select user from dual;
160. 如何查看碎片程度高的表?
SELECT segment_name table_name , COUNT(*) extents
FROM dba_segments WHERE owner NOT IN (&＃39;SYS&＃39;, &＃39;SYSTEM&＃39;) GROUP BY segment_name
HAVING COUNT(*) &＃61; (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);
162. 如何知道表在表空间中的存储情况?
select segment_name,sum(bytes),count(*) ext_quan from dba_extents where
tablespace_name&＃61;&＃39;&tablespace_name&＃39; and segment_type&＃61;&＃39;TABLE&＃39; group by tablespace_name,segment_name;
163. 如何知道索引在表空间中的存储情况?
select segment_name,count(*) from dba_extents where segment_type&＃61;&＃39;INDEX&＃39; and owner&＃61;&＃39;&owner&＃39;
group by segment_name;
164、如何知道使用cpu多的用户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#&＃61;11 and c.sid&＃61;a.sid and a.paddr&＃61;b.addr order by value desc;
165. 如何知道监听器日志文件?
以8I为例
$ORACLE_HOME.NETWORK/LOG/LISTENER.LOG
166. 如何知道监听器参数文件?
以8I为例
$ORACLE_HOME/NETWORK/ADMIN/LISTENER.ORA
167. 如何知道TNS 连接文件?
以8I为例
$ORACLE_HOME/NETWORK/ADMIN/TNSNAMES.ORA
168. 如何知道Sql*Net 环境文件?
以8I为例
$ORACLE_HOME/NETWORK/ADMIN/SQLNET.ORA
169. 如何知道警告日志文件?
以8I为例
$ORACLE_HOME/ADMIN/SID/BDUMP/SIDALRT.LOG
170. 如何知道基本结构?
以8I为例
$ORACLE_HOME/rdbms/ADMIN/STANDARD.SQL
171. 如何知道建立数据字典视图?
以8I为例
$ORACLE_HOME/RDBMS/ADMIN/CATALOG.SQL
172. 如何知道建立审计用数据字典视图?
以8I为例
$ORACLE_HOME/RDBMS/ADMIN/CATAUDIT.SQL
173. 如何知道建立快照用数据字典视图?
以8I为例
$ORACLE_HOME/RDBMS/ADMIN/CATSNAP.SQL
待续...
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