Join two tables in HIVE with sub query - hadoop

Question

I need to get the cost of an item at a certain date and time. I have these two tables:
create table sales ( product_id int, items_sold int, date_loaded date );
create table product ( product_id int, description string, item_cost double, date_loaded date );
The product table is a history of each item. If the cost of an item today is $1.00 but the cost of that item yesterday was $0.99 I would have two records one for each day. When I load my sales data I need to reflect the cost of the item yesterday and not today's cost.
Here is the query I am trying to execute:
SELECT s.product_id, s.items_sold, p.description, s.items_sold * p.item_cost as total_cost FROM sales s, product p
WHERE
p.product_id = s.product_id and
p.date_loaded <= (
SELECT MAX(pp.date_loaded)
FROM product pp
WHERE
pp.product_id = s.product_id and
pp.date_loaded <= s.date_loaded
)
SALES TABLE:
|PRODUCT_ID |ITEMS_SOLD |DATE_LOADED |
|1 |4 |2016-06-30 |
|1 |5 |2016-07-01 |
|1 |6 |2016-07-02 |
|1 |3 |2016-07-03 |
PRODUCT TABLE:
|PRODUCT_ID |DESCRIPTION |ITEM_COST |DATE_LOADED |
|1 |ITEM A |0.99 |2016-06-20 |
|1 |ITEM A |1.00 |2016-07-02 |
I would expect to see this result:
|PRODUCT_ID |ITEMS_SOLD |DESCRIPTION |ITEM_COST |TOTAL_COST |
|1 |4 |ITEM A |0.99 |3.96 |
|1 |5 |ITEM A |0.99 |4.95 |
|1 |6 |ITEM A |1.00 |6.00 |
|1 |3 |ITEM A |1.00 |3.00 |
From everything I have read this form of a sub query is not allowed. So how can I accomplish this in HIVE?

Answer 1

It can be accomplished with CTE and Lag widow function
With result as(select PRODUCT_ID, DESCRIPTION, ITEM_COST , DATE_LOADED ,
LEAD(DATE_LOADED, 1,'2999-01-01')
OVER (ORDER BY DATE_LOADED) AS fromdate from PRODUCT )
SELECT s.product_id, s.items_sold, p.description, s.items_sold * p.item_cost
as total_cost FROM sales s join result p on s.product_id = p.product_id
where s.DATE_LOADED >= p.DATE_LOADED and s.DATE_LOADED < p.fromdate ;