new report combined query

select
	report.report_date,
	sum(sum_new_users_b) sum_new_users,
	sum(sum_active_users_b) sum_active_users,
	sum(sum_sessions_b) sum_sessions,
	sum(sum_total_minutes_a) sum_total_minutes
from (
	select
		a.report_date,
		0 sum_new_users_b,
		0 sum_active_users_b,
		0 sum_sessions_b,
		sum(a.total_minutes) sum_total_minutes_a
	from report_total_minutes_by_hour_actual a
	where a.report_date >= '2015-03-01'
		and a.report_date <= '2015-03-31'
		and a.gateway_id in (<gateway_id>)
	group by a.report_date
	union
	select
		b.report_date,
		sum(b.new_users) sum_new_users_b,
		sum(b.active_users) sum_active_users_b,
		sum(b.sessions) sum_sessions_b,
		0 sum_total_minutes_a
	from report_by_did_2015_1 b
		inner join data_entryway c on b.entryway_id = c.id
	where b.report_date >= '2015-03-01'
		and b.report_date <= '2015-03-31'
		and c.gateway_id in (<gateway_id>)
	group by b.report_date
) report
group by report.report_date