HardSQL challenge #351CALCULATIONORDER BYANALYSIS

Calculate the Average Value per Item of Each Order

Return every order with its total divided by its item count, highest value per item first.

The challenge runs on the SQLabHub practice database (SQLite) and uses the orders table. You can solve it in the browser, with nothing to install.

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The task

Find orders with highest value per item.

A correct answer returns 200 rows with 11 columns: id, user_id, total, discount, item_count, status, order_date, shipped_date, shipping_city, shipping_country, density.

Tables used in this challenge

`orders` 200 rows

id INTEGER (PK) · user_id INTEGER · total REAL · discount REAL · item_count INTEGER · status TEXT · order_date TEXT · shipped_date TEXT · shipping_city TEXT · shipping_country TEXT

First 3 rows of the orders table
id	user_id	total	discount	item_count	status	order_date	shipped_date	shipping_city	shipping_country
1	43	2638.11	0.25	3	cancelled	2024-04-24	NULL	Los Angeles	USA
2	8	2947	0.19	5	delivered	2024-03-15	2023-04-09	Chicago	USA
3	136	683.24	0.08	2	delivered	2023-02-15	2023-07-10	Los Angeles	USA

The first rows of each table are shown. See how all the tables relate on the database schema page.

Expected output

Expected output of the challenge
id	user_id	total	discount	item_count	status	order_date	shipped_date	shipping_city	shipping_country	density
192	49	4936.98	0.06	1	refunded	2023-01-12	NULL	Charlotte	USA	4936.98
127	5	4924.23	0.22	1	delivered	2024-05-18	2024-03-21	Phoenix	USA	4924.23
164	77	4770.01	0.11	1	delivered	2023-03-18	2024-10-26	Dallas	USA	4770.01
34	122	4754.8	0.02	1	cancelled	2022-05-26	NULL	Houston	USA	4754.8
97	51	4566.23	0.16	1	delivered	2024-12-09	2023-01-27	Los Angeles	USA	4566.23

First 5 of 200 rows. This is the output of the model solution on the practice database.

What you practise

Sorting the result with ORDER BY
Deriving a new column from an expression and naming it with an alias

Hint and approach

Try the challenge first. Open these only when you need them.

Show the hint

total / item_count

Show the step-by-step approach

How the model solution is built, in the order the database evaluates it:

Read from the orders table.
Add the calculated column density: total * 1.0 / item_count.
Sort the result by density descending.

Model solution

Checking your session…

What to watch for

Dividing two integers in SQLite truncates the result, which is why total is multiplied by 1.0 first. Here total is already REAL, so the factor is a safeguard; with two integer columns it changes the answer.

Calculated columns. Dividing one integer by another truncates the result in SQLite. Multiply one side by 1.0 to get decimals.
ORDER BY. Without ORDER BY the row order is not guaranteed, even if it looks stable. Rows that tie on the sort columns can come back in any order.

Solve This SQL Challenge

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Same technique, other tables

More practice on this pattern with different columns:

Keep learning

Lesson: Comments & Aliases
Lesson: ORDER BY
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SQL Playground: run any query on the same database