MediumSQL challenge #178DATE

Find Orders That Took More Than 3 Days to Ship

Return the orders where more than three days passed between ordering and shipping.

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 where shipping took more than 3 days.

A correct answer returns 65 rows with 10 columns: id, user_id, total, discount, item_count, status, order_date, shipped_date, shipping_city, shipping_country.

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
3	136	683.24	0.08	2	delivered	2023-02-15	2023-07-10	Los Angeles	USA
5	140	1120.99	0.13	4	delivered	2023-06-16	2023-12-21	Denver	USA
6	50	1327.01	0.08	5	shipped	2024-02-16	2024-12-13	Seattle	USA
8	91	4163.77	0.2	2	delivered	2022-01-17	2023-08-22	Indianapolis	USA
13	2	1618.29	0.23	3	delivered	2023-04-02	2024-04-02	Seattle	USA

First 5 of 65 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

Returning every column of a table with SELECT *
Filtering rows with a WHERE condition
Working with dates in SQLite: strftime, julianday and DATE

Hint and approach

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

Show the hint

Use julianday

Show the step-by-step approach

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

Read from the orders table.
Filter in WHERE: keep the rows where the number of days from order_date to shipped_date is greater than 3.
Return every column with SELECT *.

Model solution

Checking your session…

What to watch for

julianday() turns a date into a day number, so subtracting two of them gives days. Unshipped orders have a NULL difference and drop out. In this practice dataset shipped_date is random and sometimes earlier than order_date, so the pattern is real but the delays are not.

Date functions. These date functions are SQLite syntax. MySQL uses DATE_FORMAT and DATEDIFF, PostgreSQL uses TO_CHAR, EXTRACT and date subtraction.
WHERE. WHERE is evaluated before the SELECT list, so it cannot use a column alias defined there or the result of an aggregate.
SELECT *. SELECT * is fine for exploring, but its output changes whenever a column is added to the table. Queries that feed a report should name their columns.

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