Oracle : Allocated, Used & Free space within datafiles

REM ------------------------------------------------------------------------------
REM Filename: dffree.sql
REM Purpose: Shows current size, used & freespace within the datafiles.
REM Author: Kam Muhamad Sirajdin [mdsirajdin@yahoo.com]
REM ------------------------------------------------------------------------------

TTI "Allocated, Used & Free space within datafiles"

COLUMN free_space_mb format 999999.90
COLUMN allocated_mb format 999999.90
COLUMN used_mb format 999999.90

SELECT SUBSTR (df.NAME, 1, 40) file_name, df.bytes / 1024 / 1024 allocated_mb,
((df.bytes / 1024 / 1024) - NVL (SUM (dfs.bytes) / 1024 / 1024, 0))
used_mb,
NVL (SUM (dfs.bytes) / 1024 / 1024, 0) free_space_mb
FROM v$datafile df, dba_free_space dfs
WHERE df.file# = dfs.file_id(+)
GROUP BY dfs.file_id, df.NAME, df.file#, df.bytes
ORDER BY file_name;

TTI off