oracle维护常用语句
1、查看表空间的名称及大小
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、查看表空间物理文件的名称及大小
select tablespace_name, file_id, file_name, round(bytes/(1024*1024),0) total_space from dba_data_files order by tablespace_name;
3、查看回滚段名称及大小
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$logfile;
6、查看表空间的使用情况
select sum(bytes)/(1024*1024) as free_space,tablespace_name from dba_free_space group by tablespace_name; SELECT A.TABLESPACE_NAME,A.BYTES TOTAL,B.BYTES USED, C.BYTES FREE, (B.BYTES*100)/A.BYTES "% USED",(C.BYTES*100)/A.BYTES "% FREE" FROM SYS.SM$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、查看数据库库对象
select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;
8、查看数据库的版本
Select version FROM Product_component_version Where SUBSTR(PRODUCT,1,6)='Oracle';
9、查看数据库的创建日期和归档方式
Select Created, Log_Mode, Log_Mode From V$Database;
10、查看当前所有对象
SQL> select * from tab;
11、建一个和a表结构一样的空表
SQL> create table b as select * from a where 1=2; SQL> create table b(b1,b2,b3) as select a1,a2,a3 from a where 1=2;
12、察看数据库的大小，和空间使用情况
SQL> col tablespace format a20 SQL> select b.file_id
文件ID, b.tablespace_name
表空间, b.file_name
物理文件名, b.bytes
总字节数, (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 --表空间剩余空间状况
dba_data_files --数据文件空间占用情况
13、查看现有回滚段及其状态
SQL> col segment format a30 SQL> SELECT SEGMENT_NAME,OWNER,TABLESPACE_NAME,SEGMENT_ID,FILE_ID,STATUS FROM DBA_ROLLBACK_SEGS;
14、查看数据文件放置的路径
SQL> col file_name format a50 SQL> select tablespace_name,file_id,bytes/1024/1024,file_name from dba_data_files order by file_id;
15、显示当前连接用户
SQL> show user
16、把SQL*Plus当计算器
SQL> select 100*20 from dual;
17、连接字符串
SQL> select 列1||列2 from 表1; SQL> select concat(列1,列2) from 表1;
18、查询当前日期
SQL> select to_char(sysdate,'yyyy-mm-dd,hh24:mi:ss') from dual;
19、用户间复制数据
SQL> copy from user1 to user2 create table2 using select * from table1;
20、视图中不能使用order by，但可用group by代替来达到排序目的
SQL> create view a as select b1,b2 from b group by b1,b2;
21、通过授权的方式来创建用户
SQL> grant connect,resource to test identified by test; SQL> conn test/test
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