????????????????????

????????????????????????????????????????Oracle???????????????????

???????????????????????????????Э????????????????л?????????????????衣

?????????????????????????

????Oracle??????????????????????DML??????????????????????????????л????????????????????DDl???????????????????????????

?????????commit???????DDL????С?

??????????????????????????????Щ?????????????????????е???????????????????????????????????κ????????????????????в?????where????update?????????????????????????????????????????????sql???Oracle?????????????dba?????????????????????????Щ??????????????????????????????????????δ???????????????????????????????????????????????????????????????

?????????????????????????????????е??????????ó???????????????????????????????????

???????￡????λ?????С???????emp???е??????У????????????????????????????5??????????????????????Щ?С?

SQL> delete from emp;
15 rows deleted.
SQL> commit;
Commit complete.
SQL> select count(*) from emp;
COUNT(*)
----------
0
SQL> insert into emp (select * from emp as of timestamp(sysdate-5/1440));
15 rows created.
SQL> select count(*) from emp;
COUNT(*)
----------
15
??2?????????????????????????
????:
SQL> drop table emp;
Table dropped.
SQL> select count(*) from emp;
select count(*) from emp
*
ERROR at line 1:
ORA-00942: table or view does not exist
SQL> flashback table emp to before drop;
Flashback complete.
SQL> select count(*) from emp;
COUNT(*)
----------
15

???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????仯??????????????????????????????????????????????????????????????????????????????й????????????????????????