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
)
让我们说我有一件T恤(product_id = 1),大小M的颜色为蓝色,属性更多。
我尝试过加入这三个表,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”,则此选项有效。和尺寸'但是如果我有更多的属性,那就说X选择会太长。
选择怎么样? 还有其他解决办法吗?
我找到了解决方案。它很难看,但它能完成这项工作。但是,如果产品有,请说10个规格,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
将此查询与您喜欢的规范相匹配。如果有人有更好的解决方案,请发布。
答案 0 :(得分:0)
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:
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)