关于合并两个表数据的SQL方法

今天遇到一个功能，需要在两个结构一样的表中统计预约方式的个数，关键点在于union all 和sum的使用

select sum(y1) as y,a.name
from(SELECT
        count(1) as y1,
        sdd.dict_label as name
FROM
ars_appointment_info aai
        JOIN sys_dict_data sdd
        on sdd.dict_value=aai.AppointmentChannel AND sdd.dict_type = 'ars_appointment_info_AppointmentChannel'
                where AppointmentDate >='2020-6-2'
                and AppointmentDate <= '2020-6-8'
        GROUP BY
        AppointmentChannel union all  
        SELECT
        count(1) as y2,
        sdd.dict_label as name
FROM
ars_appointment_info_non aai
        JOIN sys_dict_data sdd
        on sdd.dict_value=aai.AppointmentChannel AND sdd.dict_type = 'ars_appointment_info_AppointmentChannel'
                where AppointmentDate >='2020-6-2'
                and AppointmentDate <= '2020-6-8'
        GROUP BY
        AppointmentChannel) as a
        GROUP BY a.name