Using a Join as the Dominant or Subordinate Part of an Outer Join

Suppose you want to modify the previous query (the post-join filter example) to get more information that will help you determine whether to continue carrying each unsold item in the catalog. You can modify the query to include information from the stock table so that you can see a short description of each unsold item with its cost:

SELECT c.catalog_num, c.stock_num, s.description, s.unit_price, 
   s.unit_descr, c.manu_code, i.quantity
FROM (catalog c INNER JOIN stock s
   ON c.stock_num = s.stock_num 
      AND c.manu_code = s.manu_code)
    LEFT JOIN items i
      ON c.stock_num = i.stock_num 
         AND c.manu_code = i.manu_code
   WHERE i.quantity IS NULL
      AND c.manu_code = "HRO";