Question

使用一对多方法在以下数据库设计中查询具有特定属性的产品的适当方法是什么？

我想我应该做以下事情： SELECT (*) FROM productProperties WHERE property = 'weight' AND value = '10'

但如果我需要重量= 10＆amp;的产品怎么办？同一查询中的color = blue？

数据库设计示例：

表格：产品

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

table：productProperties

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

Answer 1

如果我需要的产品怎么办？重量= 10＆amp;颜色=蓝色相同的查询？

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

子查询的另一个选项：

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'
       )

Answer 2

SELECT * FROM productProperties p 
WHERE (SELECT COUNT(*) FROM productProperties p1 WHERE p1.product = p.product AND 
( (property = 'weight' AND value = '10') OR (property = 'color' AND value = 'blue') ) 
 =2

mySQL：查询一对多-table？

2 个答案: