此文章是根据官方改变
模拟帐户转账流程
1.JOHN帐户扣除-DAVID帐户增加-记录日志－事务提交
三个操作必须全部完成此事务才完成，否则失败
创建帐户余额表自增字段自增序列；
createsequencesaving_seqincrementby1startwith1maxvalue999999999999999999nocyclecache20;
创建支票表自增字段自增序列；
createsequencecheck_seqincrementby1startwith1maxvalue999999999999999999nocyclecache20;
创建日志记录自增字段自增序列；l
create sequence log_seq increment by 1 start with 1 maxvalue 999999999999999999 nocycle cache 20 ;
2.创建余额表saving_accounts
createtablesaving_accounts
(account_idintprimarykey,
account_namevarchar2(20) ,
paynumber(15,2) );
commentontablesaving_accountsis '帐户余额表';
commentoncolumnsaving_accounts.account_idis'帐户ID';
commentoncolumnsaving_accounts.account_nameis'帐户名称';
commentoncolumnsaving_accounts.payis'帐户余额';
创建支票余额表
createtablechecking_accounts
(check_idintprimarykey,
check_namevarchar2(20) ,
check_paynumber(15,2) );
commentontablechecking_accountsis '支票帐户余额表';
commentoncolumnchecking_accounts.check_idis'支票帐户ID';
commentoncolumnchecking_accounts.check_nameis'支票帐户名称';
commentoncolumnchecking_accounts.check_payis'支票帐户余额';
创建转账日志表
createtablelog_accounts
(log_idintprimarykey,
log_datedate default(sysdate)notnull,
account_idintnotnull,
check_idintnotnull,
change_paynumber(15,2) );
commentontablelog_accountsis '转账日志表';
commentoncolumnlog_accounts.log_idis'转账日志ID';
commentoncolumnlog_accounts.log_dateis'转账日期';
commentoncolumnlog_accounts.account_idis'转账帐户ID';
commentoncolumnlog_accounts.check_idis'支票帐户ID';
commentoncolumnlog_accounts.change_payis'支票帐户余额';
查询建表是否成功
select*fromlog_accounts;
select*fromsaving_accounts;
select*fromchecking_accounts;
3.插入数据
插入 saving_accounts
insert into saving_accounts
values(saving_seq.nextval,'john',1000);
insert into saving_accounts
values(saving_seq.nextval,'david',2000);
insert into saving_accounts
values(saving_seq.nextval,'alex',3000);
insert into saving_accounts
values(saving_seq.nextval,'lily',5000);
insert into saving_accounts
values(saving_seq.nextval,'joe',1500);
commit;
插入checking_accounts
insert into checking_accounts
values( check_seq.nextval,'john',2000);
insert into checking_accounts
values( check_seq.nextval,'david',500);
insert into checking_accounts
values( check_seq.nextval,'alex',2000);
insert into checking_accounts
values( check_seq.nextval,'lily',1500);
insert into checking_accounts
values( check_seq.nextval,'joe',4000);
commit;
用户转账的步骤（转账到支票）
如john
防止事务失败可以加入异常处理
begin
savepoint sp1
--SET TRANSACTION NAME 'account_update'; 可以设置事务名称transaction name
--减少john 帐户余额200转入到david
update saving_accounts a
set pay=pay-200
where a.account_id=1;
--SAVEPOINT after_update_savind_accounts; 设置rollback点
--增加david支票余额
update checking_accounts b
set check_pay=check_pay+200
where b.check_id=2;
--写入日志表
insert into log_accounts(log_id,account_id,check_id,change_pay)
values(log_seq.nextval,1,2,200);
--ROLLBACK TO SAVEPOINT after_update_savind_accounts; 回滚到saingpoint after_update_savind_accounts
--rollback 将回滚事务account_update
exception
when others then
rollback to savepoint sp1;
end;
when others then
rollback to savepoint sp1;
end;
commit work;
总结:
如果在一个 SQL 语句在执行过程中发生了错误，那么此语句对数据库产生的影响将被回滚（roll back）。回滚后就如同此语句从未执行过。
