To shrink datafiles as much as possible

select 'alter database datafile '''||file_name||''' resize ' || ceil( (nvl(hwm,1)*&&blksize)/1024/1024 )  || '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.TABLESPACE_NAME='TEST_OIM' and a.file_id = b.file_id(+) and ceil( blocks*&&blksize/1024/1024) - ceil( (nvl(hwm,1)*&&blksize)/1024/1024 ) > 0;