Oracle restore table, table deletes data by mistake, oracle flashback

The oracle recovery table deletes data by mistake, and restores the deleted table and its data

Preparatory work (all steps 1 and 2 must be operated by system users):
1. Open the archive log

#查看归档日志是否开启
su - oracle
sqlplus / as sysdba
SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     28
Next log sequence to archive   30
Current log sequence           30


#开启归档日志
su - oracle
sqlplus / as sysdba

SQL>shutdown immediate;
SQL>startup mount;
SQL>alter database  archivelog; 
SQL>alter database open;
SQL>archive log list;

2. Turn on flashback

su - oracle
sqlplus / as sysdba

#检查是否开启闪回
SQL> select flashback_on from v$database;
FLASHBACK_ON
------------------
NO

#开启闪回
SQL> alter database flashback on;

1. Accidentally deleted data and small data recovery

#查询表tableA被删除的数据，这里时间'xxxx-xx-xx xx:xx:xx'指该时间点前tableA的表数据。
#注意：该时间不能是未来时间。举个栗子，现在时间是2020-10-26 09:12:00。执行查询2020-10-26 10:12:00前的数据，
#就会报ORA-08186: 指定的时间戳无效，因为2020-10-26 10:12:00是未来时间
select * from tableA as of timestamp
to_timestamp('xxxx-xx-xx xx:xx:xx','yyyy-mm-dd hh24:mi:ss')
where tableA中字段 not in  (
      select tableA中字段 from tableA
)

#恢复tableA中被删除的数据（将'xxxx-xx-xx xx:xx:xx'前不存在于现在时间tableA表的数据插入到tableA中）
INSERT INTO  tableA select * from tableA as of timestamp
to_timestamp('xxxx-xx-xx xx:xx:xx','yyyy-mm-dd hh24:mi:ss')
where tableA中字段 not in  (
      select tableA中字段 from tableA
)


#实例
#查询B_IMAGE_LOG 中被删除的数据（'2020-10-26 09:12:00'前的B_IMAGE_LOG中数据和现在的B_IMAGE_LOG做对比）
select * from B_IMAGE_LOG as of timestamp
to_timestamp('2020-10-26 09:12:00','yyyy-mm-dd hh24:mi:ss')
where busi_num not in  (
      select busi_num from B_IMAGE_LOG
)

#恢复B_IMAGE_LOG 中被删除的数据
INSERT INTO  B_IMAGE_LOG select * from B_IMAGE_LOG as of timestamp
to_timestamp('2020-10-26 09:12:00','yyyy-mm-dd hh24:mi:ss')
where busi_num not in  (
      select busi_num from B_IMAGE_LOG
)

Two, flashback table (update/insert/delete)

#闪回表就是对表的数据做回退，回退到之前的某个时间点，其利用的是undo的历史数据，与undo_retention设置有关，默认是900s
su - oracle
sqlplus / as sysdba
SQL> show parameter undo_ 

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      UNDOTBS1
#修改undo_retention参数未10800
ALTER SYSTEM SET undo_retention=10800 SCOPE=BOTH;

#示例（以下操作为新建普通用户）
#启用行移动功能
alter table TEST enable row movement;
#恢复TEST表的数据到2020-10-26 14:20:00前的数据
flashback table TEST to timestamp to_timestamp('2020-10-26 14:20:00','yyyy-mm-dd hh24:mi:ss');

3. Recover deleted tables and their data. Flashback DROP (drop table)

su - oracle
sqlplus / as sysdba
SQL> conn 用户名/用户密码; 
SQL> show recyclebin;
ORIGINAL NAME    RECYCLEBIN NAME           OBJECT TYPE   DROP TIME
TEST      BIN$souMg34DMq3gUAEKfAFufA==$0 TABLE    2020-10-26:11:39:23

#法一恢复删掉的表
flashback table TEST to before drop;
#法二按RECYCLEBIN NAME恢复删掉的表
flashback table "BIN$souMg34DMq3gUAEKfAFufA==$0" to before drop;
#恢复删掉的表，并且重命名
flashback table TEST to before drop rename to TEST2;

Reference materials: https://www.jb51.net/article/130703.htm