SQL
Retrieve Related Data with LEFT JOIN
Master how to use LEFT JOIN to retrieve records from one table along with all matching records from another, including cases where no match exists in the second table.
SELECT u.id, u.username, p.title AS post_title, p.created_at AS post_date
FROM users u
LEFT JOIN posts p ON u.id = p.user_id
WHERE u.status = 'active'
ORDER BY u.username, p.created_at DESC;
How it works: `LEFT JOIN` returns all rows from the left table (`users`) and the matching rows from the right table (`posts`). If there's no match for a user in the `posts` table, the columns from `posts` will be `NULL`. This is ideal for displaying users and their posts, even if a user has not created any posts yet.