oracle相关操作
查询锁表
SELECT /*+ rule */ lpad(' ',decode(l.xidusn ,0,3,0))||l.oracle_username User_name,
o.owner,o.object_name,o.object_type,s.sid,s.serial#
FROM v$locked_object l,dba_objects o,v$session s
WHERE l.object_id=o.object_id
AND l.session_id=s.sid
ORDER BY o.object_id,xidusn DESC;
解锁                       'sid,serial'
alter system kill session '553,6';

查询正在执行的存储过程：
select name from v$db_object_cache where locks > 0 and pins > 0 and type='PROCEDURE'

查询某个表空间里所有表的大小：
select sum(d.bytes) / 1024 / 1024 / 1024 || 'G' as total_bytes,
       d.tablespace_name
  from dba_data_files d
where d.tablespace_name = 'BASE01'
group by d.tablespace_name

查询表空间数据文件名及其大小：
select t.file_name,t.bytes from dba_data_files t where t.tablespace_name='UNDOTBS1';
查询某个表空间里的表：
select table_name,tablespace_name from user_tables where tablespace_name='UNDOTBS1';

查询表空间使用情况
   select df.tablespace_name
   "Tablespace",df.bytes/(1024*1024)
   "Total Size(MB)",
   sum(fs.bytes)/(1024*1024) "Free
   Size(MB)",
   round(sum(fs.bytes)*100/df.bytes)
   "% Free",
   round((df.bytes-sum(fs.bytes))*100/
   df.bytes) "% Used"
   from dba_free_space fs,
   (select tablespace_name,
   sum(bytes) bytes from
   dba_data_files group by
   tablespace_name ) df
   where fs.tablespace_name(+) =
   df.tablespace_name
   group by df.tablespace_name,
   df.bytes;

查询数据库连接数
select count(*) from v$process  -- 数据库当前连接数
select value from v$parameter where name = 'processes' – 数据库所允许的最大连接数

查看服务器上的数据库：oracle用户登陆服务器，sqlplus '/as sysdba'，select username from dba_users;