select * from v$version;

select decode(sign(变量1 - 变量2), -1, 变量1, 变量2) from dual; --取较小值

select segment_name,
       tablespace_name,
       bytes B,
       bytes / 1024 KB,
       bytes / 1024 / 1024 MB
  from user_segments
 where segment_type = ‘TABLE‘;

SELECT l.session_id sid,
       s.serial#,
       l.locked_mode,
       l.oracle_username,
       l.os_user_name,
       s.machine,
       s.terminal,
       o.object_name,
       s.logon_time
  FROM v$locked_object l, all_objects o, v$session s
 WHERE l.object_id = o.object_id
   AND l.session_id = s.sid
 ORDER BY sid, s.serial#;

alter system kill session ‘sid,serial#‘; --结合上面查询死锁结果使用

select a."MACHINE", a."PROGRAM", a."PREV_EXEC_START", a.terminal
  from v$session a
 where a.username = ‘HRPDEV‘;

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;

select tablespace_name,
       file_id,
       file_name,
       round(bytes / (1024 * 1024), 0) total_space
  from dba_data_files
 order by tablespace_name;

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;

select name from v$controlfile; 

select member from v$logfile; 

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;

select owner, object_type, status, count(*) count#
  from all_objects
 group by owner, object_type, status;