我有三个数据库表:
products
(
product_id, name etc..
)
specifications
(
id_specification, name
)
product_has_specification
(
id_specification, product_id, specification_value
)
假设我有一件T恤(product_id = 1),大小M的颜色为蓝色,属性更多 .
我已经尝试加入这三个表并且值= m AND value = blue等 . 但它不显示任何结果 .
我也试过像这样的子查询:
select distinct products.* from products
join product_has_specification on products.id = product_has_specification.product_id
join specifications on product_has_specification.spec_id = pecifications.id_specification
where
(
(specifications.name = 'color' and product_has_specification.value='black')
)
and products.id in
(
select products.id from products
left join product_has_specification on products.id = product_has_specification.product_id
left join specifications on product_has_specification.spec_id = specifications.id_specification
where
(specifications.name='size' and product_has_specification.value='s')
)
如果产品的颜色为“黑色”且尺寸为“s”,则此选择有效;但如果我有更多属性,则说X选择将太长 .
选择怎么样?还有其他解决方案吗?
编辑:
我找到了解决方案 . 它很难看,但它能完成这项工作 . 但是,如果一个产品,让我们说10个规格的查询很长 .
SELECT products.*
FROM products
left JOIN product_has_specification ON products.id = product_has_specification.product_id
left JOIN specifications ON product_has_specification.id_specifiction = specifications.id_specification
WHERE products.id in (
SELECT products.id
FROM products
left JOIN product_has_specification ON products.id = product_has_specification.product_id
left JOIN specifications ON product_has_specification.id_specifiction = specifications.id_specification
where (product_has_specification.value = 'm') and products.id in
(
SELECT products.id
FROM products
left JOIN product_has_specification ON products.id = product_has_specification.product_id
left JOIN specifications ON product_has_specification.id_specifiction = specifications.id_specification
where (product_has_specification.value = 'black') and products.id in
(
SELECT products.id
FROM products
left JOIN product_has_specification ON products.id = product_has_specification.product_id
left JOIN specifications ON product_has_specification.id_specifiction = specifications.id_specification
where (product_has_specification.value = 'test')
)
)
)
group by products.id
使此查询适应您想要的任意数量的规范 . 如果有人有更好的解决方案,请发布 .
1 回答
您可以使用EXISTS和AND运算符选择所有颜色为黑色且尺寸为s的产品: