Question

I hope the title somehow makes sense.

I’ve got 3 tables in DB. First one holds product_variant records, second one holds the label records and the third one is the ref table in between.

• product_variant: (id, productId, serviceProviderId).
• label: (id,label).
• product_variant_label_ref: (label_id,variant_id).

Input parameters for my query are: productType, serviceProviderId and set of labels and
my aim is to select rows in product_variant table based on the input parameters.

This is my query in hibernate xml file:

 SELECT v.*
 FROM product_variant v
     INNER JOIN product_variant_label_ref r ON v.id = r.variant_id
     INNER JOIN product_product p ON p.productType = :productType
     INNER JOIN product_label l ON l.id = r.label_id
     WHERE v.product_id = p.id
        AND v.serviceprovider_id = :serviceProviderId
        AND l.label in (:labels)

Problem is that with IN operator I am getting disjunctive OR selection and I want AND in between. If I specify different labels as an input, I want only those product_variant rows which have a relation to all of them through ref table. If one of the input labels doesn’t belong to any product_variant, query should not return anything. Could anyone help me to change my query?

Answer 1

You need to count the rows returned for each product, and match it to the number of items in your labels parameter

If you have, for example, 3 labels in your labels parameter…

 SELECT v.id
 FROM product_variant v 
     INNER JOIN product_variant_label_ref r ON v.id = r.variant_id 
     INNER JOIN product_product p ON p.productType = :productType 
     INNER JOIN product_label l ON l.id = r.label_id 
     WHERE v.product_id = p.id 
        AND v.serviceprovider_id = :serviceProviderId 
        AND l.label in (:labels) 
 GROUP BY v.id
 HAVING COUNT(DISTINCT l.id) = 3 -- ie: Length of labels