使用子查询加入HIVE中的两个表

Question

我需要在特定日期和时间获得商品的费用。我有这两个表：

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 );

产品表是每个项目的历史记录。如果今天的物品成本是1.00美元，但昨天该物品的成本是0.99美元，我每天会有两个记录。当我加载销售数据时，我需要反映昨天该项目的成本，而不是今天的成本。

以下是我要执行的查询：

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 |

产品表：

|PRODUCT_ID |DESCRIPTION |ITEM_COST |DATE_LOADED | |1 |ITEM A |0.99 |2016-06-20 | |1 |ITEM A |1.00 |2016-07-02 |

我希望看到这个结果：

|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 |

从我读过的所有内容都不允许这种形式的子查询。那么我怎样才能在HIVE中实现这一目标呢？

Answer 1

可以使用CTE和Lag widow function

来完成

     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  ;