What value does the 'running' column hold for each employee, given this triangular self-join?

-- emp(id, dept): (1,'Eng'), (2,'Eng'), (3,'Eng'), (4,'Sales') SELECT a.id, COUNT(b.id) AS running FROM emp a JOIN emp b ON b.dept = a.dept AND b.id <= a.id GROUP BY a.id ORDER BY a.id;