LEFT JOIN
(
	SELECT
		COUNT(b.id) AS c_id,
		LEFT(b.start_date, 10) AS date,
		b.professional_user_id
	FROM patient_doctor pd
	GROUP BY date
	UNION SELECT
		COUNT(c.id) AS c_id,
		LEFT(c.inactivation_date, 10) AS date,
		c.professional_user_id
	FROM patient_doctor pd
	GROUP BY date
) x
ON x.professional_user_id = a.id