HardSQL challenge #202WINDOW FUNCTIONRANKINGORDER

Rank Orders by Total with DENSE_RANK()

Assign every order a dense rank by its total, largest 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.

Solve This SQL Challenge

The task

Assign dense rank to orders based on total.

A correct answer returns 200 rows with 3 columns: id, total, rnk.

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	total	rnk
123	4997.15	1
114	4980.63	2
192	4936.98	3
94	4926.49	4
127	4924.23	5

First 5 of 200 rows. This is the output of the model solution on the practice database. The task does not fix a sort order, so your rows may come back in a different order.

What you practise

Ranking rows with RANK() or DENSE_RANK() and handling ties

Hint and approach

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

Show the hint

DENSE_RANK()

Show the step-by-step approach

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

Read from the orders table.
Rank the rows with DENSE_RANK(), ordered by total descending. Tied rows share a rank and no rank number is skipped.

Model solution

Checking your session…

What to watch for

DENSE_RANK() gives tied rows the same number and continues with the next integer, so the highest rank equals the number of distinct totals. RANK() would leave gaps after ties, and ROW_NUMBER() would never tie.

RANK() and DENSE_RANK(). RANK() skips numbers after a tie (1, 1, 3) and DENSE_RANK() does not (1, 1, 2). Filtering on rank <= N returns more than N rows when there are ties.