select Total.Tname "表空间名称",Total.Total_Size "表空间大小",
Total.Total_Size - Used.free_size as "已使用大小",Used.Free_size as 表空间剩余大小,

Round((Total.Total_Size - Used.free_size) / Total.Total_Size,4)* 100 || '%' as 表空间使用率

from

(

-- 表空间数据文件的大小

select tablespace_name as TName,round(sum(user_bytes)/(1024*1024),1) as Total_size from dba_data_files

group by tablespace_name

) Total,

(

-- 表空间剩余的大小

select tablespace_name as TName,round(sum(bytes)/(1024*1024),1) as Free_size from dba_free_space

group by tablespace_name

) Used

where Total.TName = Used.TName(+)