Question

我有很多关系的表：

参数

+-------------------+-----------------------+
| Field             | Type                  |
+-------------------+-----------------------+
| id                | int(11)               |
| name              | varchar(20)           |

产品

+-------------------+-----------------------+
| Field             | Type                  |
+-------------------+-----------------------+
| id                | int(11)               |
| name              | varchar(20)           |

Parameters_Product

+-------------------+-----------------------+
| Field             | Type                  |
+-------------------+-----------------------+
| id_parameters     | int(11)FK             |
| id_product        | int(11)FK             |

因此，产品可能有一些参数，参数可能与产品有关。当我选择几个参数时，我需要输出包含已检查参数的产品的已排序名称，但排序必须基于匹配参数的数量，但不止一个。

示例：

Parameters_Product

+---------+----------+
|id_param |id_product|
+--------------------+
| 1       | 1        | 
| 2       | 1        | ----> Product#1
| 3       | 1        | 
| 4       | 1        | 
----------------------
| 1       | 2        |
| 2       | 2        |
| 6       | 2        | ----> Product#2
| 4       | 2        |
| 9       | 2        |
----------------------
| 5       | 3        |
| 7       | 3        | ----> Product#3
| 1       | 3        |

客户选择Id_params：1,2,6,9。

按顺序结果：

Product#2 -> 4 matches
Product#1 -> 2 matches
Product#3 -> 1 matches (doesn't outputted)

我在php中使用可怕的代码完成了它，但我认为它可以更容易解决。

如何在SQL中执行此操作？

Answer 1

您必须按id_product字段进行分组，使用id_param值过滤单个结果，然后按id_param计数排序。像这样：

SELECT name
FROM Parameters_Product
 INNER JOIN Parameters ON id_product = id
WHERE id_param IN (1,2,6,9)
GROUP BY id_product
HAVING COUNT(id_param) > 1
ORDER BY COUNT(id_param) desc

Answer 2

如果您只需要id_product：

select id_product,
count(id_param) as matches 
from Parameters_Product
where
id_param in (1,2,6,9)
group by id_product
having count(id_param) >1
order by matches desc;

如果您需要产品名称：

select p.name,count(pp.id_param) as matches 
from 
Product p
join Parameters_Product pp
on p.id=pp.id_product
where
pp.id_param in (1,2,6,9)
group by p.name
having count(pp.id_param) >1
order by matches desc;

OR

select p.name,pp.matches from Product p
join
(select id_product,
count(id_param) as matches 
from Parameters_Product
where
id_param in (1,2,6,9)
group by id_product
having count(id_param) >1) pp
on p.id = pp.id_product
order by pp.matches desc;

如何对联结表

2 个答案: