HardSQL challenge #328DATECALCULATIONORDER BY

Max Shipping Delay

Find orders with maximum shipping delay.

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 maximum shipping delay.

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, delay.

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
iduser_idtotaldiscountitem_countstatusorder_dateshipped_dateshipping_cityshipping_country
1432638.110.253cancelled2024-04-24NULLLos AngelesUSA
2829470.195delivered2024-03-152023-04-09ChicagoUSA
3136683.240.082delivered2023-02-152023-07-10Los AngelesUSA

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
iduser_idtotaldiscountitem_countstatusorder_dateshipped_dateshipping_cityshipping_countrydelay
1507129.170.063delivered2022-02-112024-12-16San AntonioUSA1039
13064151.020.134shipped2022-01-232024-10-27IndianapolisUSA1008
921064695.260.086delivered2022-01-262024-06-07DallasUSA863
18424259.070.133delivered2022-06-172024-10-07JacksonvilleUSA843
54742921.570.231delivered2022-06-132024-10-03ColumbusUSA843

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

What you practise

  • Working with dates in SQLite: strftime, julianday and DATE
  • 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

julianday diff

Show the step-by-step approach

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

  1. Read from the orders table.
  2. Add the calculated column delay: julianday(shipped_date) - julianday(order_date).
  3. Sort the result by delay descending.

Model solution

Checking your session…

What to watch for

  • Date functions. These date functions are SQLite syntax. MySQL uses DATE_FORMAT and DATEDIFF, PostgreSQL uses TO_CHAR, EXTRACT and date subtraction.
  • 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.
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