refactor 1251

Author: fishercoder1534

database/_1251.sql

@@ -1,75 +1,7 @@
---1251. Average Selling Price
---
---Table: Prices
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| product_id    | int     |
---| start_date    | date    |
---| end_date      | date    |
---| price         | int     |
---+---------------+---------+
---(product_id, start_date, end_date) is the primary key for this table.
---Each row of this table indicates the price of the product_id in the period from start_date to end_date.
---For each product_id there will be no two overlapping periods. That means there will be no two intersecting periods for the same product_id.
---
---
---Table: UnitsSold
---
---+---------------+---------+
---| Column Name   | Type    |
---+---------------+---------+
---| product_id    | int     |
---| purchase_date | date    |
---| units         | int     |
---+---------------+---------+
---There is no primary key for this table, it may contain duplicates.
---Each row of this table indicates the date, units and product_id of each product sold.
---
---
---Write an SQL query to find the average selling price for each product.
---
---average_price should be rounded to 2 decimal places.
---
---The query result format is in the following example:
---
---Prices table:
---+------------+------------+------------+--------+
---| product_id | start_date | end_date   | price  |
---+------------+------------+------------+--------+
---| 1          | 2019-02-17 | 2019-02-28 | 5      |
---| 1          | 2019-03-01 | 2019-03-22 | 20     |
---| 2          | 2019-02-01 | 2019-02-20 | 15     |
---| 2          | 2019-02-21 | 2019-03-31 | 30     |
---+------------+------------+------------+--------+
---
---UnitsSold table:
---+------------+---------------+-------+
---| product_id | purchase_date | units |
---+------------+---------------+-------+
---| 1          | 2019-02-25    | 100   |
---| 1          | 2019-03-01    | 15    |
---| 2          | 2019-02-10    | 200   |
---| 2          | 2019-03-22    | 30    |
---+------------+---------------+-------+
---
---Result table:
---+------------+---------------+
---| product_id | average_price |
---+------------+---------------+
---| 1          | 6.96          |
---| 2          | 16.96         |
---+------------+---------------+
---Average selling price = Total Price of Product / Number of products sold.
---Average selling price for product 1 = ((100 * 5) + (15 * 20)) / 115 = 6.96
---Average selling price for product 2 = ((200 * 15) + (30 * 30)) / 230 = 16.96
-
 select a.product_id, round(
     sum(a.price * b.units)/sum(b.units),
     2) as average_price
 from Prices as a
 join UnitsSold as b
 on a.product_id = b.product_id and (b.purchase_date between a.start_date and a.end_date)
-group by a.product_id;
-
+group by a.product_id;