set heading on;
break on report
compute sum of "total MB" on report
col "total MB" format 999,999,999,999,990
compute sum of "Free MB" on report
col "Free MB" format 999,999,999,999,990
compute sum of "Used MB" on report
col "Used MB" format 999,999,999,999,990

select
 d.tablespace_name, 
 SUBSTR(d.file_name,1,50) "Datafile name",
 ROUND(MAX(d.bytes)/1024/1024,2) as "total MB", 
 DECODE(SUM(f.bytes), null, 0, ROUND(SUM(f.Bytes)/1024/1024,2)) as "Free MB" , 
 DECODE( SUM(f.Bytes), null, 0, ROUND((MAX(d.bytes)/1024/1024) - (SUM(f.bytes)/1024/1024),2)) as "Used MB" 
from 
  DBA_FREE_SPACE f , DBA_DATA_FILES d 
where 
 f.tablespace_name(+) = d.tablespace_name 
 and f.file_id(+) = d.file_id
group by 
d.tablespace_name,d.file_name;

clear breaks