Question

1070. Product Sales Analysis III

中文文档

Description

Table: Sales

+-------------+-------+
| Column Name | Type  |
+-------------+-------+
| sale_id   | int   |
| product_id  | int   |
| year    | int   |
| quantity  | int   |
| price     | int   |
+-------------+-------+
(sale_id, year) is the primary key (combination of columns with unique values) of this table.
product_id is a foreign key (reference column) to Product table.
Each row of this table shows a sale on the product product_id in a certain year.
Note that the price is per unit.

 

Table: Product

+--------------+---------+
| Column Name  | Type  |
+--------------+---------+
| product_id   | int   |
| product_name | varchar |
+--------------+---------+
product_id is the primary key (column with unique values) of this table.
Each row of this table indicates the product name of each product.

 

Write a solution to select the product id, year, quantity, and price for the first year of every product sold.

Return the resulting table in any order.

The result format is in the following example.

 

Example 1:

Input: 
Sales table:
+---------+------------+------+----------+-------+
| sale_id | product_id | year | quantity | price |
+---------+------------+------+----------+-------+ 
| 1     | 100    | 2008 | 10     | 5000  |
| 2     | 100    | 2009 | 12     | 5000  |
| 7     | 200    | 2011 | 15     | 9000  |
+---------+------------+------+----------+-------+
Product table:
+------------+--------------+
| product_id | product_name |
+------------+--------------+
| 100    | Nokia    |
| 200    | Apple    |
| 300    | Samsung    |
+------------+--------------+
Output: 
+------------+------------+----------+-------+
| product_id | first_year | quantity | price |
+------------+------------+----------+-------+ 
| 100    | 2008     | 10     | 5000  |
| 200    | 2011     | 15     | 9000  |
+------------+------------+----------+-------+

Solutions

Solution 1

# Write your MySQL query statement below
SELECT
  product_id,
  year AS first_year,
  quantity,
  price
FROM Sales
WHERE
  (product_id, year) IN (
    SELECT
      product_id,
      MIN(year) AS year
    FROM Sales
    GROUP BY product_id
  );

Solution 2

# Write your MySQL query statement below
WITH
  T AS (
    SELECT
      *,
      RANK() OVER (
        PARTITION BY product_id
        ORDER BY year
      ) AS rk
    FROM Sales
  )
SELECT product_id, year AS first_year, quantity, price
FROM T
WHERE rk = 1;