gistfile1.sql

SELECT salesperson_id, 
     Sum(sold / salesperson_count) AS amount 
FROM   project_items 
     JOIN(SELECT allocation.project_item_id, 
           sold, 
           salesperson_id 
      FROM   project_item_sellers 
           JOIN(SELECT project_item_id, 
                 Sum(amount) AS sold 
            FROM   project_item_allocations AS allocation 
            WHERE  Year(allocation.created) = 2014 
                 AND Month(allocation.created) = 03 
            GROUP  BY project_item_id 
            HAVING sold <> 0
          ) allocation 
           ON allocation.project_item_id = 
            project_item_sellers.project_item_id 
          GROUP  BY allocation.project_item_id, salesperson_id
    ) t2 
     ON t2.project_item_id = project_items.id 
GROUP  BY salesperson_id