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;