create table AA
(
  id   NUMBER,
  name VARCHAR2(3)
);
insert into aa (id,name) values(1,'g1');

insert into aa (id,name) values(2,'g2');

select t.*, t.rowid from AA t;


commit;
--------------
insert into aa (id,name) values(3,'g3');

rollback;

insert into aa (id,name) values (4, 'g4');
insert into aa (id,name) values (5, 'g5');
savepoint A;
update aa set name='g9' where id=5;

update aa set name='g10' where id=5;
update aa set name='g11' where id=6;

savepoint B;

insert into aa (id,name) values (6, 'g6');
 rollback to B;
 rollback to A;
 commit;  --或者 rollback;

系统中有个队列，用savepoint对整个transaction的不同阶段进行标记，标记不会导致已有的命令执行。

这个过程中，如果想回滚，告知回滚到什么地方即可。

如果一条DML语句会造成多少影响，则使用sql$rowcount来看会有多少影响

https://www.cnblogs.com/langtianya/p/5067019.html