set lines 200; 
column owner format a15; 
column segment_name format a30; 

select 
	a.owner, 
	a.segment_name, 
	a.segment_type, 
	round(a.bytes/1024/1024,0) MBS, 
	round((a.bytes-(b.num_rows*b.avg_row_len) )/1024/1024,0) WASTED 
from dba_segments a, dba_tables b 
where a.owner=b.owner 
and a.owner not like 'SYS%' 
and a.segment_name = b.table_name 
and a.segment_type='TABLE' 
group by a.owner, a.segment_name, a.segment_type, round(a.bytes/1024/1024,0) ,round((a.bytes-(b.num_rows*b.avg_row_len) )/1024/1024,0) 
having round(bytes/1024/1024,0) >100 
order by round(bytes/1024/1024,0) desc ;