Oracle查询表空间的使用情况的SQL语句，很实用

SELECT   a.a1 TableSpace_Name,
c.c2 Type_,
c.c3 LocalAdmin,
b.b2 / 1024 / 1024 TS_Size,
(b.b2 - a.a2) / 1024 / 1024 Used_Size,
SUBSTR ( (b.b2 - a.a2) / b.b2 * 100, 1, 5) Used_Ratio
FROM   (  SELECT   tablespace_name a1, SUM (NVL (bytes, 0)) a2
FROM   dba_free_space
GROUP BY   tablespace_name) a,
(  SELECT   tablespace_name b1, SUM (bytes) b2
FROM   dba_data_files
GROUP BY   tablespace_name) b,
(SELECT   tablespace_name c1, contents c2, extent_management c3
FROM   dba_tablespaces) c
WHERE   a.a1 = b.b1 AND c.c1 = b.b1;