如何查看oracle 数据库

SELECT INSTANCE_NAME, VERSION, STARTUP_TIME, USERNAME
FROM v$instance;

SELECT name, value
FROM v$osstat
WHERE name IN ('NUM_CPUS', 'NUM_CPU_CORES', 'PHYSICAL_MEMORY_BYTES');

SELECT tablespace_name, total_space, free_space, (total_space-free_space) used_space
FROM (
  SELECT tablespace_name, SUM(bytes) free_space
  FROM dba_free_space
  GROUP BY tablespace_name
), (
  SELECT tablespace_name, SUM(bytes) total_space
  FROM dba_data_files
  GROUP BY tablespace_name
)
WHERE tablespace_name NOT LIKE '%TEMP%'
ORDER BY tablespace_name;

SELECT COUNT(*) FROM v$session;

SELECT SQL_ID, EXECUTIONS, ELAPSED_TIME/1000000 sec,
  BUFFER_GETS, DISK_READS, ROWS_PROCESSED
FROM v$sql
ORDER BY ELAPSED_TIME DESC;

SELECT name, value 
FROM v$sysstat 
WHERE name IN ('physical reads', 'physical writes');

SELECT TIMESTAMP, MESSAGE FROM v$system_warnings;

SELECT TIMESTAMP, MESSAGE FROM v$diag_alert_ext 
WHERE MESSAGE_TEXT LIKE '%ERROR%';

SELECT s.sid, s.status, s.username, s.osuser, s.machine, 
       s.program, s.logon_time, m.sql_text
FROM v$session s 
LEFT OUTER JOIN v$sql m ON s.sql_id = m.sql_id
WHERE s.type != 'BACKGROUND';

SELECT l.session_id, s.username, s.osuser, s.machine, s.program, 
       l.lock_type, l.mode_held, l.mode_requested, o.object_type, 
       o.owner || '.' || o.object_name
FROM v$lock l 
JOIN v$session s ON l.session_id = s.sid 
JOIN dba_objects o ON l.id1 = o.object_id;