HAVING

HAVING filters groups

WHERE filters individual rows before grouping. HAVING is applied after grouping and lets you keep only groups that satisfy an aggregate condition.

SELECT customer_id, COUNT(*) AS order_count
FROM orders
GROUP BY customer_id
HAVING COUNT(*) >= 5;

First, orders are grouped by customer_id, then the row count is calculated for each group, and only groups with five or more orders remain in the result.

WHERE and HAVING can work together

SELECT customer_id, SUM(amount) AS total
FROM orders
WHERE status = 'PAID'
GROUP BY customer_id
HAVING SUM(amount) > 10000;

WHERE first keeps only paid orders. They are then grouped by customer, after which HAVING keeps customers whose total payments exceed 10000.