ORDER BY, LIMIT, DISTINCT

Three small but indispensable verbs: ORDER BY (sort), LIMIT (cap rows), DISTINCT (remove duplicates). You'll use them in nearly every interactive query.

ORDER BY

SELECT first_name, last_name, signed_up_at
FROM customers
ORDER BY signed_up_at DESC;

DESC = descending (newest first). ASC = ascending (default). You can sort by multiple columns:

SELECT *
FROM orders
ORDER BY country ASC, total_amount DESC;

First sort by country (A-Z), then within each country sort by total_amount (high-to-low).

LIMIT

SELECT * FROM orders
ORDER BY total_amount DESC
LIMIT 10;

Top 10 orders by amount. LIMIT is essential for exploration — never run a SELECT * on a million-row table without one.

DISTINCT

SELECT DISTINCT country FROM customers ORDER BY country;

Returns the unique list of countries. DISTINCT applies to the entire row in the SELECT — DISTINCT a, b returns unique (a, b) pairs, not unique a OR unique b.