查看表空间使用情况

 select   username,default_tablespace   from   dba_users;
 select t.tablespace_name,
       round(t.bytes / 1024 / 1024 / 1024, 2) || 'G' "总大小",
       round((t.bytes - f.bytes) / 1024 / 1024 / 1024, 2) || 'G' "已使用",
       round(100 * (t.bytes - f.bytes) / t.bytes, 2) || '%' "使用率"
  from (select tablespace_name, sum(bytes) bytes
          from dba_data_files
         group by tablespace_name) t,
       (select tablespace_name, sum(bytes) bytes
          from dba_free_space
         group by tablespace_name) f
 where f.tablespace_name(+) = t.tablespace_name