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

 1 select sum(y1) as y,a.name
 2 from(SELECT
 3         count(1) as y1,
 4         sdd.dict_label as name
 5 FROM
 6 ars_appointment_info aai
 7         JOIN sys_dict_data sdd
 8         on sdd.dict_value=aai.AppointmentChannel AND sdd.dict_type = \'ars_appointment_info_AppointmentChannel\'
 9                 where AppointmentDate >=\'2020-6-2\'
10                 and AppointmentDate <= \'2020-6-8\'
11         GROUP BY
12         AppointmentChannel union all  
13         SELECT
14         count(1) as y2,
15         sdd.dict_label as name
16 FROM
17 ars_appointment_info_non aai
18         JOIN sys_dict_data sdd
19         on sdd.dict_value=aai.AppointmentChannel AND sdd.dict_type = \'ars_appointment_info_AppointmentChannel\'
20                 where AppointmentDate >=\'2020-6-2\'
21                 and AppointmentDate <= \'2020-6-8\'
22         GROUP BY
23         AppointmentChannel) as a
24         GROUP BY a.name