如何在MySQL中创建具有N:M关系的表?
假设我有两个表:Store和Product。我希望我的商店有产品清单。我怎样才能做到这一点?
create table store(id int unsigned not null auto_increment,
store_name varchar(30) not null,
product_list_FK int unsigned not null,
primary key(id)
);
create table product(
id int unsigned not null auto_increment,
product_name varchar(30) not null,
price float not null,
primary key(id)
);
我开始这样的事情,但是我不知道该如何完成,你们能帮我吗?
回答:
多对一(产品只能有一家商店)
create table store( id int unsigned not null auto_increment,
store_name varchar(30) not null,
primary key(id)
);
Query OK, 0 rows affected (0.02 sec)
create table product(
id int unsigned not null auto_increment,
store_id int unsigned not null,
product_name varchar(30) not null,
price float not null,
primary key(id),
constraint product_store foreign key (store_id) references store(id)
);
Query OK, 0 rows affected (0.02 sec)
多对多(产品可以在许多商店中使用)
create table store( id int unsigned not null auto_increment,
store_name varchar(30) not null,
primary key(id)
);
Query OK, 0 rows affected (0.04 sec)
create table product(
id int unsigned not null auto_increment,
store_id int unsigned not null,
product_name varchar(30) not null,
price float not null,
primary key(id)
);
Query OK, 0 rows affected (0.01 sec)
create table product_store (
product_id int unsigned not null,
store_id int unsigned not null,
CONSTRAINT product_store_store foreign key (store_id) references store(id),
CONSTRAINT product_store_product foreign key (product_id) references product(id),
CONSTRAINT product_store_unique UNIQUE (product_id, store_id)
)
Query OK, 0 rows affected (0.02 sec)
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