📊 AggregationbeginnerCommonly used

How to use SUM, AVG, MIN and MAX in SQL

Calculate totals, averages, and extremes across rows.

SUM — total of a columnAll databases

SELECT SUM(total) AS revenue
FROM orders
WHERE status = 'completed';

Adds up all values in the column. NULL values are ignored.

AVG — average valueAll databases

SELECT
  AVG(age)   AS avg_age,
  ROUND(AVG(age), 1) AS avg_age_rounded
FROM users;

Calculates the arithmetic mean. Use ROUND() to control decimal places.

MIN and MAXAll databases

SELECT
  MIN(total) AS smallest_order,
  MAX(total) AS largest_order,
  MAX(created_at) AS latest_order
FROM orders;

MIN and MAX work on numbers, dates, and strings.

Multiple aggregates in one queryAll databases

SELECT
  COUNT(*)           AS total_orders,
  SUM(total)         AS revenue,
  AVG(total)         AS avg_order_value,
  MIN(total)         AS min_order,
  MAX(total)         AS max_order
FROM orders
WHERE status = 'completed';

Combine multiple aggregate functions in one query.

Aggregates per groupAll databases

SELECT
  country,
  COUNT(*)   AS users,
  AVG(age)   AS avg_age,
  MAX(age)   AS oldest
FROM users
GROUP BY country
ORDER BY users DESC;

All aggregate functions work with GROUP BY.

Common Mistakes

→All aggregate functions ignore NULL values — this can give misleading results
→AVG of integers gives a decimal — wrap in ROUND() if needed

Common Mistakes

Related Topics