LeetCode 1068: Product Sales Analysis I

Problem Restatement

We have two tables:

Sales(sale_id, product_id, year, quantity, price) — each row is a sale.

Product(product_id, product_name) — product information.

We need to return product_name, year, and price for each sale.

Input and Output

Return a table with product_name, year, price.

Examples

Sales:                           Product:
+---------+------------+------+  +------------+--------------+
| sale_id | product_id | year |  | product_id | product_name |
+---------+------------+------+  +------------+--------------+
| 1       | 100        | 2008 |  | 100        | Nokia        |
| 2       | 100        | 2009 |  | 200        | Apple        |
| 7       | 200        | 2011 |  | 300        | Samsung      |
+---------+------------+------+  +------------+--------------+

Answer:

+--------------+------+-------+
| product_name | year | price |
+--------------+------+-------+
| Nokia        | 2008 | ...   |
| Nokia        | 2009 | ...   |
| Apple        | 2011 | ...   |
+--------------+------+-------+

Edge Cases

• Match the aggregate to the question: use raw COUNT or SUM for rows/amounts, and COUNT(DISTINCT ...) only for unique entities.
• Tie cases should return every qualifying row unless the statement asks for a single row.
• For outer joins, keep filters on the joined table in the ON clause when unmatched rows must remain visible.

Common Pitfalls

• Do not put aggregate filters in WHERE; use HAVING after GROUP BY.
• When the answer needs all tied winners, avoid LIMIT 1 unless the statement explicitly asks for one row.

Implementation

SELECT p.product_name, s.year, s.price
FROM Sales s
JOIN Product p ON s.product_id = p.product_id;

Code Explanation

Join Sales with Product on product_id to get the product name for each sale.

Select product_name, year, and price from the joined result.