使用存储过程操作数据表

go 
use db_Test;
if exists (select * from sysobjects where name='book')
drop table book;
create table book(
	bookId int primary key,bookName char(20),bookPrice float,publishTime date
);
--创建存储过程,向book表中插入10条数据
go
if exists (select * from sysobjects where name='addBook')
drop procedure addBook;
go
create procedure addBook as
begin
	declare @i int;
	set @i=1;
	while(@i<10)
	begin
		--cast 将一个表达式转化成另外一个类型
		insert into book select @i,'book '+cast(@i as CHAR(1)),(10+@i)/10.0,GETDATE();
		set @i=@i+1;
	end
end
go
--执行存储过程
exec addBook;

--创建带参数的存储过程：@id表示所借书ID @money表示钱，result 表示借书结果
if exists(select * from sysobjects where name='borrowBook')
drop procedure borrowBook;
go
create procedure borrowBook @id int,@money float,@result bit output as
begin
	declare @bookPrice float;
	--获取所借书本的价格
	select @bookPrice=bookPrice from book where bookId=@id;
	if(@money>=@bookPrice)
		begin
		set @result=1;
		print '可以借书';
		end
	else
		begin
		set @result=0;
		print '不能借书';
		end
end 
go
--执行存储过程
declare @result bit;
--使用output 返回参数
exec borrowBook 1,1.3,@result output;
select case 
			when @result=0 then '不能借书'
			when @result=1 then '可以借书' end as '能否借书';

--修改存储过程：将borrowBook的返回值的类型改为char
go
alter procedure borrowBook @id int,@result char(20) output as
begin
	declare @bookPrice float;
	--获取所借书本的价格
	select @bookPrice=bookPrice from book where bookId=@id;
	if(@money>=@bookPrice)
		begin
		set @result='可以借书';
		end
	else
		begin
		set @result='不能借书';
		end
end 
go
declare @re char(20);
exec borrowBook 1,1.2,@re output;
select @re as '能否借书';