--1、查看表空间的名称及大小
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;
--2、查看表空间物理文件的名称及大小
SELECT tablespace_name,
file_id,
file_name,
round(bytes / (1024 * 1024), 0) total_space
FROM dba_data_files
ORDER BY tablespace_name;
--3、查看回滚段名称及大小
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$rollstat v
WHERE r.segment_id = v.usn(+)
ORDER BY segment_name;
--4、查看控制文件
SELECT NAME FROM v$controlfile;
--5、查看日志文件
SELECT MEMBER FROM v$logfile;
--6、查看表空间的使用情况
SELECT SUM(bytes) / (1024 * 1024) AS free_space, tablespace_name
FROM dba_free_space
GROUP BY tablespace_name;
SELECT a.tablespace_name,
a.bytes total,
b.bytes used,
c.bytes free,
(b.bytes * 100) / a.bytes "% USED ",
(c.bytes * 100) / a.bytes "% FREE "
FROM sys.sm$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;
--7、查看数据库库对象
SELECT owner, object_type, status, COUNT(*) count#
FROM all_objects
GROUP BY owner, object_type, status;
--8、查看数据库的版本　
SELECT version
FROM product_component_version
WHERE substr(product, 1, 6) = 'Oracle';
--9、查看数据库的创建日期和归档方式
SELECT created, log_mode, log_mode FROM v$database;

--1G=1024MB
--1M=1024KB
--1K=1024Bytes
--1M=11048576Bytes
--1G=1024*11048576Bytes=11313741824Bytes
SELECT a.tablespace_name "表空间名",
total "表空间大小",
free "表空间剩余大小",
(total - free) "表空间使用大小",
total / (1024 * 1024 * 1024) "表空间大小(G)",
free / (1024 * 1024 * 1024) "表空间剩余大小(G)",
(total - free) / (1024 * 1024 * 1024) "表空间使用大小(G)",
round((total - free) / total, 4) * 100 "使用率 %"
FROM (SELECT tablespace_name, SUM(bytes) free
FROM dba_free_space
GROUP BY tablespace_name) a,
(SELECT tablespace_name, SUM(bytes) total
FROM dba_data_files
GROUP BY tablespace_name) b
WHERE a.tablespace_name = b.tablespace_name