DISTINCT with aggregates

Count unique values with COUNT(DISTINCT ...).

DISTINCT and ORDER BY

DISTINCT and ORDER BY can be combined. Deduplication happens first, then sorting.

SELECT DISTINCT city FROM customers
ORDER BY city;

This query sorts unique cities alphabetically.

city is selected from customers (DISTINCT removes duplicates). The result is sorted by city in ascending order.

ORDER BY must use one of the DISTINCT columns; otherwise it is ambiguous. DESC gives descending order.

Select unique cities alphabetically from customers.

Show example solution

SELECT DISTINCT city
FROM customers
ORDER BY city

Sorted distinct

SELECT DISTINCT city FROM customers
____ city;

Show answer

SELECT DISTINCT city FROM customers
ORDER BY city;