DISTINCT: a list of cities without duplicates

Laras has the list of customer names and cities, but the same city appears many times (Jakarta alone has 5 customers). To ask the courier about coverage, she only needs the list of cities, each one once.

Task

Show one column, city, from the customers table, with each city appearing only once. The result has 8 rows. Any row order is fine.

Databasetokotables & columns are listed in the right panel

Required keywordsDISTINCT

Expected result

Loading the expected result…

Check answerCtrlShiftEnter
Run previewCtrlEnter
Previous / next exerciseAlt←→
Leave the workspaceEscTab

Hint 1
The word DISTINCT removes duplicate result rows, so each value appears only once.
Hint 2
DISTINCT goes right after SELECT, before the column name.
Hint 3
SELECT ___ city FROM customers;

Reveal them one at a time. The last hint nearly gives the answer away.

Give it a try first. The solution unlocks automatically after your first check.

Answer

SELECT DISTINCT city
FROM customers;

Explanation

SELECT DISTINCT city takes the city column of the 24 customers and removes the duplicates. The result is 8 cities: Jakarta, Surabaya, Bandung, Yogyakarta, Medan, Semarang, Denpasar and Makassar.
Often missed: DISTINCT applies to the combination of all selected columns, not just the first one. SELECT DISTINCT city, segment returns every unique pair of city and segment, so Jakarta can appear more than once (Retail and Corporate).
If you also want to know how many customers each city has, that is a job for GROUP BY and COUNT, which you will learn later.

SQL· database toko

SELECT city
FROM customers;

Loading the SQL editor…

Write the SQL query, run it to see the result, then press Check answer.

Validation result