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;