SolveWithSQL

Difficulty: Beginner → Early Intermediate
Estimated time: 15–20 minutes
SQL concepts: SUM(), GROUP BY, ORDER BY, aggregation logic
Goal: Sort grouped, aggregated results by a calculated value.

The Challenge

The product manager asks:

“Which product categories generate the highest total value?”

This is a classic business question:

• Not just how much per category
• But which categories matter most

To answer it, you must aggregate first, then sort.

Database Table

products

column_name	type	description
product_id	INTEGER	Unique product ID
name	TEXT	Product name
category	TEXT	Product category
price	DECIMAL	Product price

Sample Data

product_id	name	category	price
101	Wireless Mouse	Accessories	24.99
102	Mechanical Keyboard	Accessories	89.00
103	Webcam	Accessories	59.99
104	Monitor	Displays	229.99
105	USB-C Hub	Accessories	34.50
106	Laptop Stand	Workspace	39.99

Your Task

Write a SQL query that returns:

• Each category
• The total value of products in that category
• Sorted from highest total value to lowest

Expected Output

category	total_value
Accessories	208.48
Displays	229.99
Workspace	39.99

(Exact order may vary depending on sample data — sorting is the key.)

Constraints

• Use SUM()
• Use GROUP BY
• Use ORDER BY
• Sort by the aggregated value
• Do not use SELECT *

Hint (Optional)

You can sort by:

• The aggregate function itself
• Or its alias

Both are valid in most SQL dialects.

Explanation

Let’s break it down:

1. GROUP BY category
   Groups products into categories.
2. SUM(price)
   Calculates the total value per category.
3. ORDER BY total_value DESC
   Sorts categories from highest to lowest total value.

This is a foundational pattern for:

• Rankings
• Leaderboards
• Performance dashboards
• Business prioritization

Key Insight

SQL always aggregates before it sorts.

Understanding this order prevents a huge class of logical errors.

Common Mistakes

• Trying to use ORDER BY before aggregation
• Sorting by price instead of SUM(price)
• Forgetting DESC when ranking from highest to lowest

Optional Extension (Mini Bonus)

Try answering these:

1. Sort categories by lowest total value first
2. Show only categories with total value above 100
3. Sort by total value, then alphabetically by category

Next Challenge

Beginner Challenge #29: Limiting Grouped Results (Top-N with Aggregates)

Why this challenge matters

This is where SQL starts answering strategic questions:

“What should we focus on first?”

Once learners can aggregate + sort, they’re one step away from top-N analysis, which is everywhere in analytics.

🔗 View reference solution on GitHub
(After you’ve tried the challenge)

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