Question

I have a PRODUCTS table, and each product can have multiple attributes so I have an ATTRIBUTES table, and another table called ATTRIBPRODUCTS which sits in the middle. The attributes are grouped into classes (type, brand, material, colour, etc), so people might want a product of a particular type, from a certain brand.

PRODUCTS
product_id
product_name

ATTRIBUTES
attribute_id
attribute_name
attribute_class

ATTRIBPRODUCTS
attribute_id
product_id

When someone is looking for a product they can select one or many of the attributes. The problem I’m having is returning a single product that has multiple attributes. This should be really simple I know but SQL really isn’t my thing and past a certain point I get a bit lost in the logic. The problem is I’m trying to check each attribute class separately so I want to end up with something like:

SELECT DISTINCT products.product_id
FROM         attribproducts 
INNER JOIN products ON attribproducts.product_id = products.product_id
WHERE     (attribproducts.attribute_id IN (9,10,11)
AND        attribproducts.attribute_id IN (60,61))

I’ve used IN to separate the blocks of attributes of different classes, so I end up with the products which are of certain types, but also of certain brands. From the results I’ve had it seems to be that AND between the IN statements that’s causing the problem.

Can anyone help a little? I don’t have the luxury of completely refactoring the database unfortunately, there is a lot more to it than this bit, so any suggestions how to work with what I have will be gratefully received.

Answer 1

Take a look at the answers to the question SQL: Many-To-Many table AND query. It’s the exact same problem. Cletus gave there 2 possible solutions, none of which very trivial (but then again, there simply is no trivial solution).