SQL Aggregate Functions: COUNT, SUM, AVG, MIN, and MAX

Last updated: August 27, 2026.

Aggregate functions calculate one result from multiple rows. The most common are COUNT, SUM, AVG, MIN, and MAX.

Summarize an entire table

SELECT
    COUNT(*) AS order_count,
    SUM(total_amount) AS total_revenue,
    AVG(total_amount) AS average_order,
    MIN(total_amount) AS smallest_order,
    MAX(total_amount) AS largest_order
FROM orders;

COUNT(*) counts rows. Other aggregates normally ignore NULL values in their input expression.

Calculate one result per group

SELECT
    customer_id,
    COUNT(*) AS order_count,
    SUM(total_amount) AS total_spent
FROM orders
GROUP BY customer_id
ORDER BY total_spent DESC;

Every selected column that is not aggregated should normally appear in GROUP BY. This form works consistently across major SQL databases.

Count distinct values

SELECT COUNT(DISTINCT customer_id) AS active_customers
FROM orders
WHERE order_date >= '2026-01-01';

Handle an empty aggregate

SELECT COALESCE(SUM(total_amount), 0) AS total_revenue
FROM orders
WHERE order_date >= '2030-01-01';

Except for COUNT, an aggregate over no matching rows commonly returns NULL. COALESCE can supply a suitable default. See the MySQL aggregate function reference.