should return an error, the select part is read last by the DB, so whatever you define in the select part (employees_no) is not available to the having clause.

should return an error, the select part is read last by the DB, so whatever you define in the select part (employees_no) is not available to the having clause. SELECT department_id, count(*) AS employees_no FROM employee WHERE gender = 'F' GROUP BY department_id HAVING count(*) < 10; The logical order in which the DB processes the query is: FROM Employee WHERE gender = 'F' GROUP BY department_id HAVING count(*) < 10 SELECT department_id, count(*) as employees_no so you apply count(*) < 10 after you filtered by gender and after you grouped by department_id