Query to get Used,Free & total Soace of Each Tablespace

SELECT Total.name "Tablespace Name",

Free_space,

(total_space-Free_space) Used_space,

total_space

FROM

(select tablespace_name, sum(bytes/1024/1024) Free_Space

from sys.dba_free_space

group by tablespace_name

) Free,

(select b.name, sum(bytes/1024/1024) TOTAL_SPACE

from sys.v_$datafile a, sys.v_$tablespace B

where a.ts# = b.ts#

group by b.name

) Total

WHERE Free.Tablespace_name = Total.name;