Leçon 8 sur 9
GROUP BY et agrégats
GROUP BY regroupe les lignes qui ont les mêmes valeurs. Utilisez des fonctions d’agrégation comme COUNT(), SUM(), AVG(), MAX() et MIN() pour calculer des valeurs par groupe.
SQL
-- Count users per country
SELECT country, COUNT(*) as total_users
FROM users
GROUP BY country;
-- Average price per category
SELECT category, AVG(price) as avg_price
FROM products
GROUP BY category;
-- Having filters groups (like WHERE for groups)
SELECT country, COUNT(*) as total
FROM users
GROUP BY country
HAVING total > 10;