Question

I have 3 tables: Products, ProductProperties, Properties. I need to get all products, which do not have “Property B”. Tables:

# Products          # Join table                  # Properties
+----+-----------+  +------------+-------------+  +-------------+---------------+
| id | name      |  | product_id | property_id |  | property_id | property_name |
+----+-----------+  +------------+-------------+  +-------------+---------------+
|  1 | Product 1 |  |          1 |           1 |  |           1 |   Propeprty A |
|  2 | Product 2 |  |          1 |           2 |  |           2 |   Propeprty B |
|  3 | Product 3 |  |          2 |           1 |  +-------------+---------------+
+----+-----------+  |          2 |           2 |
                    |          3 |           1 |
                    +------------+-------------+

In this particular case I expect Product 3 to be returned.

Is it possible to get all required products within a single db query? What the smallest query possible to achieve that?

Edited. Queries with sub-queries considered bad.

Answer 1

Seems like you want an OUTER JOIN and then a WHERE clause to bring back the non-matched Properties. This is untested, but:

SELECT Products.* FROM 
Products RIGHT OUTER JOIN Join_Table 
  ON Products.ID = Join_Table.Product_ID
  AND Join_Table.Property_ID = 2
WHERE Products.ID IS NULL