mySQL:查询一对多表？

Question

在以下采用一对多方法的数据库设计中查询具有特定属性的产品的合适方法是什么？

我想我应该做如下的事情:SELECT (*) FROM productProperties WHERE property = 'weight' AND value = '10'

但是，如果我需要在同一查询中同时具有 weight = 10 和 color = blue 的产品怎么办？

数据库设计示例:

表:产品

------------------------
id    | name     |  price
------------------------
0     | myName   |  100
1     | myName2  |  200

表:productProperties

------------------------------------------------
product  | property     |  Value
------------------------------------------------
0        | weight       |  10
1        | weight       |  20
1        | color        |  blue

Answer 1

What if I need to products that has both weight = 10 & color = blue in the same query?

一个选项:

select product, name
  from products inner join productProperties
    on (products.id = productProperties.product)
 where (property = 'weight' and value = '10')
    or (property = 'color' and value = 'blue')
 group by product, name
having count(1) = 2

子查询的另一种选择:

select id, name
  from products p
 where exists (
         select 1
           from productProperties pp1
          where p.id = pp1.product 
            and pp1.property = 'weight'
            and value = '10'
       )
   and exists (
         select 1
           from productProperties pp2
          where p.id = pp2.product 
            and pp2.property = 'color'
            and value = 'blue'
       )