Find Products That Have Never Been Ordered

SQL coding challenge · Difficulty: easy · Topic: Joins · +50 XP

Problem

The catalogue team wants to archive products that have never been sold. Find all products with zero order history.

Tables

Table: products

| product_id | product_name | category_id | stock_quantity |
| --- | --- | --- | --- |
| 1 | T-Shirt | 1 | 50 |
| 2 | Jeans | 1 | 0 |
| 3 | Sneakers | 2 | 30 |
| 4 | Backpack | 2 | 0 |
| 5 | Watch | 3 | 15 |
| 6 | Sunglasses | 3 | 10 |

Table: categories

| category_id | category_name |
| --- | --- |
| 1 | Apparel |
| 2 | Footwear |
| 3 | Accessories |

Table: order_items

| item_id | product_id | quantity | unit_price | order_date |
| --- | --- | --- | --- | --- |
| 1 | 1 | 5 | 599 | 2024-05-01 |
| 2 | 3 | 2 | 2499 | 2024-05-01 |
| 3 | 2 | 3 | 1299 | 2024-05-02 |
| 4 | 5 | 1 | 1499 | 2024-05-02 |
| 5 | 3 | 4 | 2499 | 2024-05-03 |
| 6 | 1 | 2 | 599 | 2024-05-03 |
| 7 | 2 | 1 | 1299 | 2024-06-01 |
| 8 | 4 | 2 | 899 | 2024-06-01 |
| 9 | 5 | 4 | 1499 | 2024-06-02 |

Table: product_reviews

| review_id | product_id | rating |
| --- | --- | --- |
| 1 | 1 | 5 |
| 2 | 1 | 4 |
| 3 | 1 | 3 |
| 4 | 2 | 4 |
| 5 | 2 | 3 |
| 6 | 3 | 5 |
| 7 | 3 | 5 |
| 8 | 4 | 2 |
| 9 | 5 | 4 |
| 10 | 5 | 5 |

Expected Output

| product_id | product_name |
| --- | --- |
| 6 | Sunglasses |

Return: product_id, product_name
Products that appear in zero order_items rows
Sort by product_id ascending
Hint: LEFT JOIN order_items + WHERE item_id IS NULL (or NOT IN subquery)

Success Criteria

Your query returns two columns: product_id, product_name.
Only products with no row at all in order_items appear.
A product that was ordered once is not 'never ordered'.
The rows match the Expected Output exactly, with no extras.

What this SQL challenge teaches you

“Find Products That Have Never Been Ordered” is a easy-level SQL challenge focused on Joins. Working through it gives you hands-on practice with LEFT JOIN, IS NULL, NULL Check, Never ordered — the kind of transformation you are asked to write in real data engineering work and in technical interviews. You can solve it directly in the browser: the dataset is pre-loaded, so you write the query or DataFrame code, run it, and compare your output against the expected result immediately.

Concepts covered

LEFT JOIN
IS NULL
NULL Check
Never ordered

How to approach it

If you get stuck, work through these steps in order before looking at a full solution — each one narrows the problem down:

This asks for products with no matching rows at all in order_items, which is an absence rather than a value you can filter for.
A LEFT JOIN from products keeps every product and leaves NULLs where no order item matched.
Filter WHERE the order_items side IS NULL, or use NOT EXISTS. An inner join can only ever show you products that WERE ordered.

Where this comes up

Variations of this problem have been reported in interviews at Flipkart, Amazon, Databricks, Myntra. Interviewers use it to check whether you can express the logic cleanly and reason about correctness on edge cases such as ties, nulls and empty groups.

How to practise it on PySpark.in

Open the challenge, write your SQL query in the editor and press Run to execute it against the sample dataset. Submitting checks your output against every test case, including hidden ones, so you find out straight away whether your logic holds up. You can retry as often as you like, and each solved challenge adds to your XP.

Related SQL challenges

Helpful resources

Frequently asked questions

Do I need to install Spark or a database to solve this?

No. The SQL environment runs in your browser with the sample data already loaded, so there is nothing to install or configure.

Is this challenge free?

Yes - the problem, the sample dataset, the hints and unlimited test runs are free.

What level is it?

It is rated easy and covers Joins.

Solve this challenge free on PySpark.in