resize表空间

select 'alter database datafile '''||file_name||''' resize ' ||
ceil((nvl(hwm,1)*(select value from v$parameter where name='db_block_size'))/1024/1024)||'m;' cmd
from dba_data_files a,
(select file_id,max(block_id+blocks+7) hwm
from dba_extents where tablespace_name='XXXXXXX'
group by file_id) b
where b.file_id=a.file_id(+)
and ceil(blocks*(select value from v$parameter where name='db_block_size')/1024/1024)-
ceil((nvl(hwm,1)*(select value from v$parameter where name='db_block_size'))/1024/1024)>0;