Oracle subtract days/Hours from current timestamp

select to_timestamp(to_char(systimestamp + INTERVAL '-1' DAY, 'dd-mon-yy hh.mi.ss.ff4 AM')) from dual; ------ -1 day


select to_timestamp(to_char(systimestamp + INTERVAL '-2' HOUR, 'dd-mon-yy hh.mi.ss.ff4 AM')) from dual; ----- -2 hours current date time


select to_timestamp(to_char(systimestamp + INTERVAL '-1' DAY, 'dd-mon-yy hh.mi.ss.ff4 AM')) + INTERVAL '-2' HOUR from dual; ------- -2 hours -1 day

Script to recreate all tablespaces

select 'create tablespace ' || df.tablespace_name || chr(10)
 || ' datafile ''' || df.file_name || ''' size ' || df.bytes
 || decode(autoextensible,'N',null, chr(10) || ' autoextend on maxsize '
 || maxbytes)
 || chr(10)
 || 'default storage ( initial ' || initial_extent
 || decode (next_extent, null, null, ' next ' || next_extent )
 || ' minextents ' || min_extents
 || ' maxextents ' ||  decode(max_extents,'2147483645','unlimited',max_extents)
 || ') ;'
 from dba_data_files df, dba_tablespaces t
 where df.tablespace_name=t.tablespace_name