1327 List the Products Ordered in a Period

Description

Table: Products

• product_id is the primary key (column with unique values) for this table.
• This table contains data about the company’s products.

Table: Orders

• This table may have duplicate rows.
• product_id is a foreign key (reference column) to the Products table.
• unit is the number of products ordered in order_date.

Problem Statement

Write a solution to get the names of products that have at least 100 units ordered in February 2020 and their amount.

Return the result table in any order.

The result format is in the following example.

Example 1:

Input:

• Products table:

• Orders table:

Output:

Explanation:

• Products with product_id = 1 is ordered in February a total of (60 + 70) = 130.
• Products with product_id = 2 is ordered in February a total of 80.
• Products with product_id = 3 is ordered in February a total of (2 + 3) = 5.
• Products with product_id = 4 was not ordered in February 2020.
• Products with product_id = 5 is ordered in February a total of (50 + 50) = 100.

Solution

Let’s break down the problem.

1. First you need to join these two tables so that you can have information on product_name and the number of units sold.

1SELECT product_name, unit, order_date
2    FROM Products p
3    JOIN Orders o
4    ON p.product_id = o.product_id

2. You also need to focus on results from February 2020. So, you need to filter the results from that month alone. You can do this by including a filter WHERE DATE_FORMAT(order_date, '%Y-%m') = '2020-02' to the above query.
3. Next, you need to calculate the sum of unit per product. This can be done using aggregation with below query.

1SELECT product_name, SUM(unit) AS unit
2    FROM Products p
3    JOIN Orders o
4    ON p.product_id = o.product_id
5    WHERE DATE_FORMAT(order_date, '%Y-%m') = '2020-02'
6    GROUP BY product_name

4. The last thing is to filter out the results which have unit greater than or equal to 100. You can include a HAVING unit >= 100 clause for this.

The final query looks like this.

1SELECT product_name, SUM(unit) AS unit
2    FROM Products p
3    JOIN Orders o
4    ON p.product_id = o.product_id
5    WHERE DATE_FORMAT(order_date, '%Y-%m') = '2020-02'
6    GROUP BY product_name
7    HAVING unit >= 100;