oracle sql query table space usage

SELECT UPPER(D.TABLESPACE_NAME) "Tablespace_name",
D.TOT_GROOTTE_MB - nvl(F.TOTAL_BYTES,0) "Used(M)",
D.TOT_GROOTTE_MB "Tablespace_size(M)",
TO_CHAR(ROUND((D.TOT_GROOTTE_MB - nvl(F.TOTAL_BYTES,0)) / D.TOT_GROOTTE_MB * 100,
2),
'990.99') || '%' "Used%",
nvl(F.TOTAL_BYTES,0) "Available_size(M)",
decode(D.TOT_MAXBYTES_MB, 0, D.TOT_GROOTTE_MB, D.TOT_MAXBYTES_MB) "Max_Tablespace_size(M)",
decode(D.TOT_MAXBYTES_MB,
0,
TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) /
D.TOT_GROOTTE_MB * 100,
2),
'990.99') || '%',
TO_CHAR(ROUND(((D.TOT_GROOTTE_MB - F.TOTAL_BYTES)) /
D.TOT_MAXBYTES_MB * 100,
2),
'990.99') || '%') "Max_Used%",
decode(D.TOT_MAXBYTES_MB, 0, D.TOT_GROOTTE_MB, D.TOT_MAXBYTES_MB) -
(D.TOT_GROOTTE_MB - nvl(F.TOTAL_BYTES,0)) "Max_Available_size(M)"
FROM (SELECT TABLESPACE_NAME,
ROUND(SUM(BYTES) / (1024 * 1024), 2) TOTAL_BYTES
FROM SYS.DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME) F,
(SELECT DD.TABLESPACE_NAME,
ROUND(SUM(DD.BYTES) / (1024 * 1024), 2) TOT_GROOTTE_MB,
ROUND(SUM( decode(DD.MAXBYTES,0,DD.BYTES,DD.MAXBYTES)) / (1024 * 1024), 2) TOT_MAXBYTES_MB
FROM SYS.DBA_DATA_FILES DD
GROUP BY DD.TABLESPACE_NAME) D
WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+)
ORDER BY decode(D.TOT_MAXBYTES_MB,
0,
TO_CHAR(ROUND((D.TOT_GROOTTE_MB - F.TOTAL_BYTES) /
D.TOT_GROOTTE_MB * 100,
2),
'990.99') || '%',
TO_CHAR (ROUND (((D.TOT_GROOTTE_MB - F.TOTAL_BYTES)) /
D.TOT_MAXBYTES_MB * 100,
2),
'990.99') || '%') Desc;