Question

mysql提示错误语句帮忙修改一下 create table [user] ( id int identity(1,1), name varchar(20) not n

go
create table borrowBook
(
id int identity(1,1),
borrowID varchar(20) not null,
beginTime datetime not null,
endTime as (beginTime+30),
bookID varchar(20) not null,
foreign key(borrowID) references [user](borrowID),
foreign key(bookId) references book(bookid)
)
s
CREATE trigger borrow
on borrowBook
for insert
as
begin
if (select max(quantity) from book where bookid=(select top 1 bookid from inserted))>0
begin
update book set quantity=quantity-1 where bookID=(select top 1 bookid from inserted)
end
else
rollback
end

Answer 1

楼主信息完整点，把你的sql语句发出来啊

追问

create table [user]
(
id int identity(1,1),
name varchar(20) not null,
sex char(2) not null,
age int,
department varchar(20),
borrowID varchar(20) not null,
primary key(borrowID)
)
go
create table book
(
id int identity(1,1),
title varchar(100) not null,
bookID varchar(20) not null,
engine varchar(20) not null,
quantity int,
primary key(bookID)
)还有一段

追答

identity是 Transact-SQL中的用法。 你这里是要把id作为标示列，代表唯一性。可以这样写
id int(10) unsigned NOT NULL AUTO_INCREMENT,意思数字类型长度为10位数，不为空，自动增长。另外primary key 是设置主键的，一般都是id作为主键，而且自动增长，唯一性。

追问

能不能把改好的代码回答一下，麻烦了，而且问题补充还有段代码

追答

create table user
(
id int(10) unsigned NOT NULL AUTO_INCREMENT,
name varchar(20) not null,
sex char(2) not null,
age int,
department varchar(20),
borrowID int(9) not null,
primary key(id)
);
create table book
(
id int(10) unsigned NOT NULL AUTO_INCREMENT,
title varchar(100) not null,
bookID int(9) not null,
engine varchar(20) not null,
quantity int(8),
primary key(id)
);

create table borrowBook
(
id int(10) unsigned NOT NULL AUTO_INCREMENT,
borrowID int(10) references user(id),
bookID int(10) references book(id),
beginTime datetime not null,
endTime datetime not null,
primary key(id)
);