Tablespace Usage and free space with PCT

select tbs.tablespace_name,
tot.bytes/(1024*1024) "Total Space in MB",
round(tot.bytes/(1024*1024)- sum(nvl(fre.bytes,0))/(1024*1024),2) "Used in MB",
round(sum(nvl(fre.bytes,0))/(1024*1024),2) "Free in MB",
round((1-sum(nvl(fre.bytes,0))/tot.bytes)*100,2) Pct,
decode(
greatest((1-sum(nvl(fre.bytes,0))/tot.bytes)*100, 90),
90, '', '*'
) Pct_warn
from dba_free_space fre,
(select tablespace_name, sum(bytes) bytes
from dba_data_files
group by tablespace_name) tot,
dba_tablespaces tbs
where tot.tablespace_name = tbs.tablespace_name
and fre.tablespace_name(+) = tbs.tablespace_name
group by tbs.tablespace_name, tot.bytes/(1024*1024), tot.bytes
order by 5 desc, 1 ;