Departments with no employees (LEFT JOIN and IS NULL)

Three tables. departments (id, name, city). employees (id, name, email, dept_id, manager_id, salary, bonus, hire_date): dept_id and manager_id may be NULL, bonus may be NULL, hire_date is text in the form YYYY-MM-DD. orders (id, employee_id, customer, amount, status, order_date): employee_id is the sales rep (an employee id), amount may be NULL, status is DELIVERED, SHIPPED, PENDING or CANCELLED in capitals, and order_date is text in the form YYYY-MM-DD. Foreign keys are not enforced, so an order may point to an employee who does not exist.