Join two tables, matching a column with multiple values - mysql

Question

I am trying to get a product matching some custom parameters.
So I have to three tables - products, parameters and parametersitems.
Products table:
CREATE TABLE `products` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT
`Title` varchar(255) COLLATE utf8_unicode_ci NOT NULL,
`Content` longtext COLLATE utf8_unicode_ci NOT NULL,
`Price` float(10,2) unsigned NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Parameter table:
CREATE TABLE `parameters` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`Label` varchar(80) COLLATE utf8_unicode_ci NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
Parameter items table:
CREATE TABLE `parametersitems` (
`ProductID` int(10) unsigned NOT NULL DEFAULT '0',
`ParameterID` int(10) unsigned NOT NULL DEFAULT '0',
PRIMARY KEY (`ProductID`,`ParameterID`),
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
So my question is how can I get only the products matching all the parameters.
The only way I could think of is joining the parameteritems table couple of times.
For example, here is a query to get the products matching two parameters:
SELECT
products.*
FROM
products
INNER JOIN
parametersitems AS paritems1
ON
paritems1.ItemID = products.ID
AND paritems1.ParameterID = 7
INNER JOIN
parametersitems AS paritems2
ON
paritems2.ItemID = products.ID
AND paritems2.ParameterID = 11
My only concern is that the SELECT query will get slower and slower if there more parameters selected.
So is there a better way to handle this problem?
Thank you

Answer 1

Adjust the value tested in the HAVING clause to match the number of values listed in the IN clause.
SELECT p.*
FROM products p
WHERE p.ID IN (SELECT pi.ItemID
FROM parameteritems pi
WHERE pi.ItemID = p.ID
AND pi.ParameterID IN (7,11)
GROUP BY pi.ItemID
HAVING COUNT(DISTINCT pi.ParameterID) = 2)

Answer 2

select p.*
from products p
inner join (
select ItemID
from parametersitems
where ParameterID in (7, 11)
group by ItemID
having count(distinct ParameterID) = 2
) pm on p.ID = pm.ItemID

Answer 3

SELECT
p.ID, p.Title, p.Content, p.Price
FROM
products AS p
INNER JOIN
parametersitems AS pi ON pi.ProductID = p.ID
GROUP BY
p.ID, p.Title, p.Content, p.Price
HAVING COUNT(DISTINCT pi.ParameterID) = (SELECT COUNT(ID) FROM parameters);
This will always get you products matching every parameter no matter how many parameters you add. (This could become bogus if you delete a parameter without deleting the corresponding rows in paramatersitems. This is what constraints are for.)