如何对联结表中的数据进行计数和排序

Question

I have tables with many to many relationship:

Parameters

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

Product

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

Parameters_Product

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

So, product may have some parameters, parameters may relates to products. When I choose several parameters I need to output the sorted names of products which contains checked parameters, but sorting must be based on the number of match parameters, but more than one.

Example:

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        |

Client chooses Id_params: 1,2,6,9.

Result in order:

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

I did it in php with terrible code, but I think it can be resolved easier.

How to do this in SQL?

Answer 1

you have to group by id_product field, filter single results with id_param values and then order by the id_param count. like this:

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

If you need just 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;

If you need Product Name:

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;