MySQL从3个表中选择。MySQL从3个表中选择不同的产品
我有这些5个表:
CREATE TABLE `category` (
`c_id` int(6) NOT NULL AUTO_INCREMENT,
`name` varchar(40) NOT NULL,
PRIMARY KEY (c_id)
);
CREATE TABLE `product` (
`p_id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(40) NOT NULL,
`brand` varchar(30) NOT NULL,
`image_path` varchar(100) DEFAULT NULL,
PRIMARY KEY (p_id)
);
CREATE TABLE `shop` (
`s_id` int(6) NOT NULL AUTO_INCREMENT,
`name` varchar(50) NOT NULL,
`country` varchar(30) NOT NULL,
`province` varchar(30) NOT NULL,
`city` varchar(30) NOT NULL,
`suburb` varchar(30) NOT NULL,
`street` varchar(40) DEFAULT NULL,
`streetNumber` varchar(40) DEFAULT NULL,
`postalCode` int(4) DEFAULT NULL,
PRIMARY KEY (s_id)
) ;
CREATE TABLE product_category (
p_id INT NOT NULL,
c_id INT NOT NULL,
PRIMARY KEY (p_id, c_id),
FOREIGN KEY (p_id) REFERENCES Product(p_id) ON UPDATE CASCADE,
FOREIGN KEY (c_id) REFERENCES Category(c_id) ON UPDATE CASCADE
);
CREATE TABLE product_shop (
p_id INT NOT NULL,
s_id INT NOT NULL,
PRIMARY KEY (p_id, s_id),
FOREIGN KEY (p_id) REFERENCES product(p_id) ON UPDATE CASCADE,
FOREIGN KEY (s_id) REFERENCES shop(s_id) ON UPDATE CASCADE
);
基本上,产品可以有很多类别。一个类别可以分配给许多产品。一家商店可以有很多产品。产品可以在许多商店。
我想选择其中category.c_id = 2,或category.c_id = 8和shop.s_id = 1个或shop.s_id = 2
我部分的方式有与此所有产品:
select *
from product inner join product_category
on product_category.p_id=product.p_id
where (product_category.c_id=2)
or (product_category.c_id=8)
这得到所有有2个,也一个大类产品编号为8的类别编号的产品,但它得到了相同的产品两次,如果它既有category.c_id = 8,category.c_id = 2.
然后我试着让它获得独特的产品:
select DISTINCT(product.p_id) as product
from product inner join product_category
on product_category.p_id=product.p_id
where (product_category.c_id=2)
or (product_category.c_id=8)
这是现在截然不同,但没有显示足够的产品或类别的信息。我想在每一行中显示尽可能多的信息。
而下一步是只获取那些在shop.s_id = 1个或shop.s_id = 2
谁能帮我那里还是更接近?谢谢!
尝试'SELECT DISTINCT *'或'SELECT DISTINCT col1,col2 ...' –