EasyJOINs (INNER, LEFT, RIGHT, FULL)

RIGHT JOIN: show all departments even without employees

The query

SQL

SELECT
  d.dept_name,
  d.location,
  COUNT(e.emp_id) AS employee_count
FROM employees e
RIGHT JOIN departments d ON e.dept_id = d.dept_id
GROUP BY d.dept_id, d.dept_name, d.location
ORDER BY employee_count;

Tested against PostgreSQL 16

Note

“RIGHT JOIN keeps ALL rows from right table. Less common; usually rewritten as LEFT JOIN.

Tables referenced

employees10 cols
departments5 cols