oracle 查看表空间使用率

查询oracle表空间使用率，用户在管理员权限下访问。

select a.tablespace_name 表空间名,
       round(a.total_size) "表空间大小(MB)",
       round(a.total_size) - round(b.free_size, 3) "已使用空间(MB)",
       round(b.free_size, 3) "空闲空间(MB)",
       round(b.free_size / total_size * 100, 2) || '%' 使用比
  from (select tablespace_name, sum(bytes) / 1024 / 1024 total_size
          from dba_data_files
         group by tablespace_name) a,
       (select tablespace_name, sum(bytes) / 1024 / 1024 free_size
          from dba_free_space
         group by tablespace_name) b
 where a.tablespace_name = b.tablespace_name(+);