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, 'lewis', 'clerk', 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 = 20 ; 136. 将n秒转换为时分秒格式？ set serverout on declare n number := 1000000; ret varchar2(100); begin ret := trunc(n/3600) || '小时' || to_char(to_date(mod(n,3600),'sssss'),'fmmi"分 "ss"秒"') ; dbms_output.put_line(ret); end; 137. 如何查询做比较大的排序的进程？ 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. 如何查询做比较大的排序的进程的sql语句？ 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. 如何查找重复记录？ 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. 如何删除重复记录？ 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. 如何快速编译所有视图？ sql >spool view1.sql sql >select ‘alter view ‘||tname||’ compile;’ from tab; sql >spool off 然后执行view1.sql即可。 sql >@view1.sql; 142. ora-01555 snapshot too old的解决办法 增加minextents的值，增加区的大小，设置一个高的optimal值。 143. 事务要求的回滚段空间不够，表现为表空间用满（ora-01560错误），回滚段扩展到达参数 maxextents的值（ora-01628）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；增加maxextents的值。 144. 如何加密oracle的存储过程？ 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('输入参数是'||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 运行aa.plb sql> @aa.plb ; 145. 如何监控事例的等待？ select event,sum(decode(wait_time,0,0,1)) "prev", sum(decode(wait_time,0,1,0)) "curr",count(*) "tot" from v$session_wait group by event order by 4; 146. 如何回滚段的争用情况？ select name, waits, gets, waits/gets "ratio" from v$rollstat c, v$rollname d where c.usn = d.usn; 147. 如何监控表空间的 i/o 比例？ select b.tablespace_name name,b.file_name "file",a.phyrds pyr, a.phyblkrd pbr,a.phywrts pyw, a.phyblkwrt pbw from v$filestat a, dba_data_files b where a.file# = b.file_id order by b.tablespace_name; 148. 如何监控文件系统的 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. 如何在某个用户下找所有的索引？ 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. 如何监控 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$sysstat c where a.statistic# = 38 and b.statistic# = 39 and c.statistic# = 40; 151. 如何监控 sga 中字典缓冲区的命中率？ select parameter, gets,getmisses , getmisses/(gets+getmisses)*100 "miss ratio", (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "hit ratio" from v$rowcache where gets+getmisses <>0 group by parameter, gets, getmisses; 152. 如何监控 sga 中共享缓存区的命中率，应该小于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. 如何显示所有数据库对象的类别和大小？ 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. 监控 sga 中重做日志缓存区的命中率，应该小于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$latch where name in ('redo allocation', 'redo copy'); 155. 监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size select name, value from v$sysstat where name in ('sorts (memory)', 'sorts (disk)'); 156. 如何监控当前数据库谁在运行什么sql语句？ select osuser, username, sql_text from v$session a, v$sqltext b where a.sql_address =b.address order by address, piece; 157. 如何监控字典缓冲区？ 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+idle) "shared servers busy" from v$dispatcher; 此值大于0.5时，参数需加大 select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type='dispatcher'; select count(*) from v$dispatcher; select servers_highwater from v$mts; servers_highwater接近mts_max_servers时，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 ('sys', 'system') group by segment_name having count(*) = (select max( count(*) ) from dba_segments group by segment_name); 162. 如何知道表在表空间中的存储情况? 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间中的存储情况? 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#=11 and c.sid=a.sid and a.paddr=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
