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--分类表
create table pclass
(
id int identity(1,1) primary key,
comments nvarchar(20)
)
go
--products表
create table products
(
id int identity(1,1) primary key ,
pclass_id int FOREIGN KEY REFERENCES pclass(id)
)
--检索products 和class
select p.*,c.comments from products p inner join pclass c on p.pclass_id=c.id