select flashback_on from v$database;
alter database flashback on;
select * from tab_name as of timestamp to_timestamp('2008-06-03 12:00:00','yyyy-mm-dd hh24:mi:ss) where column_name=value; ## timestamp/scn
select sysdate from dual;
alter table tab_name enable row movement;
flashback table tab_name to timestamp to_timestamp('2008-06-03 12:00:00','yyyy-mm-dd hh24:mi:ss);
drop table tab_name;
show recyclebin;
select owner,original_name,object_name,ts_name,droptime,can_undrop,space from dba_recyclebin; (space以db_block為單位)
select table_name,dropped from user_tables;
flashback table tab_name to before drop;
flashback table tab_name to before drop rename to tab_name2;
flashback table "BIN$TqcduaZU07bgQJQKLDcRfg==$0" to before drop;
## if table name forgot,list the name from recyclebin)
drop table tab_name purge; ## drop table forever
purge recyclebin ## clean the recyclebin
purge dba_recyclebin; ## clean all of data owned by all user;
flashback database to scn scn_num;
flashback database to timestamp to_timestamp('2008-06-03 12:00:00','yyyy-mm-dd hh24:mi:ss);
