Correlated Subqueries in SQL — a practical guide to SQL correlated subqueries with clear examples you can reuse in real projects.
SQL Tutorial Series (57/100). Prefer one article? Read the complete SQL tutorial.
Short description
Powerful but can be slow — compare with JOIN + GROUP BY alternatives.
Correlated idea
SELECT u.email
FROM users u
WHERE EXISTS (
SELECT 1 FROM orders o
WHERE o.user_id = u.id AND o.total > 100
);