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

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