Used size of a datafile.

Content-Type: text/plain;

        charset="us-ascii"
Content-Transfer-Encoding: quoted-printable Group,
I have this query
<<<<=20
select distinct substr(a.TABLESPACE_NAME,1,10) "T N", substr(a.FILE_NAME,1,40) "F N",
 sum(a.bytes/1024/1024) "Size (M)"
 from dba_data_files a
 group by a.TABLESPACE_NAME, a.FILE_NAME  order by 1,2
>>>>

Gives me proper result, but I want to see how much of the space is used by each datafile. Which table should I refere for this query. I know this has been asked many a times, but one more time. TIA=20
Vinod.

--
http://www.freelists.org/webpage/oracle-l