I'm trying to left-join some of the 'catalog/category' attributes to a 'sales/order_item' collection. For example: a satisfying result will let me add the category-name to the order-item data.
*I know I can use the categories flat table, but I need to know if it's possible to join the EAV-collection and how.
**It must be done with one mysql query (Not by looping through the order items or something like that...)
***I know that it might lead to duplicated rows if the product has more than 1 category, that's exactly what I need.