mysql - 产品属性选择

Question

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
)

假设我有一件尺寸为 M 的 T 恤 (product_id = 1)，它具有蓝色和更多属性。

我已经尝试加入三个表，并且值 = m AND value =blue 等。但是它没有显示任何结果。

我也尝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')

 ) 

如果产品颜色为“黑色”且尺寸为“s”，则此选择有效，但是如果我有更多属性，假设 X 选择将太长。

选择会是什么样子？ 有没有其他解决办法？

编辑：

我找到了解决办法。它很丑，但它可以完成工作。但是，如果一个产品有 10 个规格，那么查询很长。

        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

将此查询调整为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。

Answer 1

您可以使用 EXISTS 和 AND 运算符来选择所有颜色为黑色和尺寸为 s 的产品：

select distinct products.* from products
WHERE
EXISTS
(select 1 from product_has_specification join specifications on product_has_specification.spec_id = specifications.id_specification
where specifications.name = 'color' and product_has_specification.value='black' and products.products.id = product_has_specification.product_id) 
and
EXISTS
(select 1 from product_has_specification join specifications on product_has_specification.spec_id = specifications.id_specification
where specifications.name='size' and product_has_specification.value='s' and products.products.id = product_has_specification.product_id)