set verify off
set pages 1000 lines 132
column file_name format a60 word_wrapped
column tablespace_name format a25 trunc
column smallest format 999,990 heading "Smallest|Size|Poss."
column currsize format 999,990 heading "Current|Size"
column savings  format 999,990 heading "Poss.|Savings"
break on report
compute sum of savings on report

column value new_val blksize
select value from v$parameter where name = 'db_block_size'
/

select tablespace_name,
       file_name,
       ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) smallest,
       ceil( blocks*&&blksize/1024/1024) currsize,
       ceil( blocks*&&blksize/1024/1024) -
       ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) savings
from dba_data_files a,
     ( select file_id, max(block_id+blocks-1) hwm
         from dba_extents
        group by file_id ) b
where a.file_id = b.file_id(+)
and a.tablespace_name like '%&&TABLESPACE%'
order by tablespace_name, file_name
/

prompt &hit_return

column cmd format a132 word_wrapped

select 'alter database datafile ''' || file_name || ''' resize '
 ||
	decode (ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ),
			1, 1,
            (1+(ceil( (nvl(hwm,1)*&&blksize)/1024/1024/100 ))*100))  || 'm;' cmd
from dba_data_files a,
     ( select file_id, max(block_id+blocks-1) hwm
         from dba_extents
        group by file_id ) b
where a.file_id = b.file_id(+)
  and ceil( blocks*&&blksize/1024/1024) -
      ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) > 0
and a.tablespace_name like '%&&TABLESPACE%'
/

undef TABLESPACE