Cheatsheet Pages / SQL Cheatsheet
LEFT JOIN in SQL — keep every row of the left table
You need the full roster, including people with no department assigned.
Every example runs against the cheatsheet's sample tables — departments(id, name), employees(id, name, dept_id, salary, manager_id, hired_on) and orders(id, emp_id, amount, ordered_on) — and was executed and verified against SQLite, so you can paste it in and get the same result.
SELECT e.name, d.name AS dept FROM employees e LEFT JOIN departments d ON e.dept_id = d.id;
-- 7 rows: Grace is there with dept = NULL. Full roster → LEFT JOIN; only matched → INNER JOIN