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),颜色为蓝色,并且具有更多属性。
我尝试连接三个表,并设置 value = m AND value =blue 等。但是它不显示任何结果。
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,但如果我有更多属性,假设 X,则选择将太长。
选择会是什么样子? 还有其他解决办法吗?
编辑:
我已经找到解决办法了。它很丑,但它能完成工作。但是,如果一个产品有,比如说 10 个规范,那么查询就会很长。
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
根据您想要的规范调整此查询。如果有人有更好的解决方案,请发布。
最佳答案
您可以使用 EXISTS 和 AND 运算符来选择所有颜色为黑色且尺寸为 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)
关于php - mysql - 产品属性选择,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/23892992/