mysql高级查询基于params选择

As first please be nice to me im a beginner with SQL language and english language. So i have problem with this query.

I've created sqlfiddle. My query look like it's working properly but I find it is not working

I would like to write a query that returns the product ID variant based on the parameters that will send

Correct query result would look like the following

PARAM = 6

id  product_id  productvariant_id   attributevalue_id 

1       3             1                     6
2       3             2                     6
---- BAD RESULTS -----
3       3             3                     6
4       3             3                     9
6       3             5                     6
7       3             6                     6
8       3             6                    11

PARAM = 6,9

id  product_id  productvariant_id   attributevalue_id 

3      3               3                   6
4      3               3                   9
---- BAD RESULTS -----
3       3              3                   6
4       3              3                   9
6       3              5                   6
7       3              6                   6
8       3              6                  11

What i really need is return productvariant_id which contains combination of inserted params, if I send only one attributevalue_id, i need to find productvariant which contain only ONE attributevalue_id. IF i send two params i finding combination of two.. not more or less

Unfortunately I do not have enough reputation for a comment, thus I have to write this as answer. Could you clarify your goal?

Do you want to retrieve the productvariant_id of all datasets where the attributevalue_id matches your parameter?

SELECT productvariant_id 
FROM productvariantattribute 
WHERE attributevalue_id IN ($YOUR_PARAMETER_LIST);

Or do you want to retrieve the productvariant_id of all datasets where the productvariant_id has only these attributevalue_ids you specified as parameter?

SELECT `productvariant_id`
FROM `productvariantattribute` 
WHERE `attributevalue_id` IN ($YOUR_PARAMETER_LIST) 
AND `productvariant_id` NOT IN (
  SELECT `productvariant_id` 
  FROM `productvariantattribute` 
  WHERE `attributevalue_id` NOT IN ($YOUR_PARAMETER_LIST)
)