数据库常用操作3

查数据库中表的任n行的记录:

select * from ( select rownum x ,tab.* from tab) where x in (2,3);

查询出数据库中表大于1000的记录:

select * from ( select rownum x ,tab.* from tab) where x>1000

如何插入'字

>select '''' from dual;

>select ascii('''') from dual;

>select chr(39) from dual;

查询字符集

select value from nls_database_parameters Where PARAMETER= 'NLS_CHARACTERSET'

修改字符集

sqlplus " / as sysdba"

SHUTDOWN IMMEDIATE;STARTUP MOUNT;

>ALTER SYSTEM ENABLE RESTRICTED SESSION;

>ALTER SYSTEM SET JOB_QUEUE_PROCESSES=0;

>ALTER DATABASE OPEN;

>ALTER DATABASE CHARACTER SET ZHS16GBK;

>SHUTDOWN IMMEDIATE; -- or NORMAL

>STARTUP;

误删除数据库文件test.dbf，启动失败

>alter database datafile 'd:\test.dbf' offline drop;

>alter database open;

输出sqlplus 结果

>spool c:\a.txt

>select * from tab;

>spool off

如何把表从一个表空间移到另一个表空间

Alter table emp move tablespace others;

在移动之后要重新rebuild索引

Alter index index_name rebuild tablespace inx;