1070. Product Sales Analysis III

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 records a sale of a product in a given year.
A product may have multiple sales entries in the same year.
Note that the per-unit price.

Write a solution to find all sales that occurred in the first year each product was sold.

• For each product_id, identify the earliest year it appears in the Sales table.

• Return all sales entries for that product in that year.

Return a table with the following columns: product_id, first_year, quantity, and price.
Return the result in any order.

 

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  |
+---------+------------+------+----------+-------+

Output: 
+------------+------------+----------+-------+
| product_id | first_year | quantity | price |
+------------+------------+----------+-------+ 
| 100        | 2008       | 10       | 5000  |
| 200        | 2011       | 15       | 9000  |
+------------+------------+----------+-------+

Solutions

Solution 1

MySQL

# 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

MySQL

# 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;

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