版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/hju22/article/details/86653794
一、实例
使用事务，完成图书馆借阅图书的操作。
1、向借阅信息表插入借阅记录
2、更新图书信息表的库存
3、更新读者信息表的余额
当库存为0或者余额小于100时，不能借书
（事务要求把借阅图书的相关操作看做一个整体，要么全部执行，要么全部不执行）
身份证号为‘330100199201231107’的读者，今天借了一本编号为’10002‘的图书,请完成图书借阅操作。
二、 相关表
需求：
1、要求一个读者借书时间为一个月
2、读者每借一本书，余额就扣除这本书价格的3%。
1、创建表
-- 创建数据库
create database book;
use book;
-- 1 图书类别表
create table category(
id int primary key auto_increment,
name varchar(20) not null,
parent_id int not null
);
-- 2 图书信息表
create table bookinfo(
book_id int primary key auto_increment,
category_id int,
book_name varchar(20) not null,
auther varchar(20) not null,
price float(6,2) not null,
press varchar(20) not null,
public_date date not null,
store int not null,
constraint fk_cate foreign key(category_id) references category(id)
)auto_increment=10000;
-- 3读者信息表
create table reader(
card_id char(18) primary key,
name varchar(20) not null,
sex enum('男','女','保密') default'保密',
age tinyint not null,
phone_number char(11) not null,
balance decimal(6,2) default 200
);
-- 4借阅信息表
create table borrowinfo(
book_id int,
card_id char(18),
borrow_date date not null,
return_date date,
is_return enum('是','否'),
constraint pk_bookid_cardid primary key(book_id,card_id),
constraint fk_bookid foreign key(book_id) references bookinfo(book_id),
constraint fk_cardid foreign key(card_id) references reader(card_id)
);
2、插入表记录
-- 1 插入类别记录
insert into category(name,parent_id) values('计算机',0),('历史',0),('英语',0),('科学',0),('数学',0),('艺术',0);
-- 2 插入图书记录
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(1,'Android权威指南','王贺',58.8,'人民邮电出版社','2016-02-01',3);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(1,'linux私房菜','鸟哥',76.5,'人民邮电出版社','2015-09-21',10);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(1,'Java编程思想','布鲁斯',110,'机械工业出版社','2008-05-30',12);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(1,'JavaScript DOM 编程艺术','吉米科',49.0,'人民邮电出版社','2016-02-01',4);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(3,'英语常用口语100句','李希',28,'南方工业出版社','2002-04-25',6);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(5,'高等数学一','王志胜',45,'吉林工业出版社','2010-04-25',6);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(5,'高等数学2','王志胜',48,'吉林工业出版社','2010-04-25',6);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(2,'三国鼎立','吴风',55,'人民出版社','2010-09-18',6);
insert into bookinfo(category_id,book_name,auther,price,press,public_date,store) values(2,'且看盛唐','文旭烟',32,'人民出版社','2013-11-29',6);
-- 3 插入读者记录
insert into reader values('330100199201231104','小明','男',29,'15787223423',300);
insert into reader values('330100199201231105','小红','女',21,'15787223424',220);
insert into reader values('330100199201231106','王迷','男',19,'15787223425',310);
insert into reader values('330100199201231107','李思','女',24,'15787223426',230);
insert into reader values('330100199201231108','小王','女',32,'15787223427',240);
insert into reader values('330100199201231109','王霞','女',26,'15787223428',300);
三、事务处理
delimiter//
create procedure borrowpro(in myid char(18),in mybookid int)
begin
declare mystore int;
declare mybalance decimal(6,2);
declare myprice float(6,2);
select store into mystore from bookinfo where book_id=mybookid;
select balance into mybalance from reader where card_id=myid;
select price into myprice from bookinfo where book_id=mybookid;
set autocommit=0; #禁止自动提交
-- 事务
insert into borrowinfo values(mybookid,myid,curdate(),date_add(curdate(),interval 1 month),'否');
update bookinfo set store=store-1 where book_id=mybookid;
update reader set balance=balance-myprice*0.03 where card_id=myid;
-- 不满足条件，回滚；否则提交事务
if mystore=0 or mybalance<100 then
rollback;
else
commit;
end if;
end//
delimiter;
call borrowpro('330100199201231107',10002);
运行结果：
执行成功，借阅表插入记录，库存和余额都更新成功。
