Mysql 如何连接三个表，从两个表中添加两个单独的字段，然后最后按两个表中两个单独的字段分组

我有三张桌子，表2，表3

管理员结构是

admins_id  | admin_name | admin_username
1          | ABC        |1234
2          | Cde        |456

table3mask |table3adminid | table3maskcount
mask1      |1              |30
mask2      |1              |70
mask3      |2              |10

表2结构为

table2mask |table2adminid | table2maskcount
mask1      |1              |30
mask2      |1              |60

表3结构为

admins_id  | admin_name | admin_username
1          | ABC        |1234
2          | Cde        |456

table3mask |table3adminid | table3maskcount
mask1      |1              |30
mask2      |1              |70
mask3      |2              |10

我想要达到的是

username   | mask        |ttlCount
1234       | mask1       | 60
1234       | mask2       | 130
456        | mask3       | 10

我应该如何做到这一点

我尝试使用下面给出的查询

SELECT admins.`admin_username`, 
(table2.`table2maskcount`+table3.`table3maskcount`) AS ttl_counts from 
admins inner join table2 on table2.`table2adminid` = admins.`admin_id` inner 
join table3 on table3.`table3adminid` = admins.`admin_id` Where 
table2.`table2mask`=table3.`table3mask`

---

但它没有给我准确的结果，它没有显示仅在其中一个表中可用的掩码计数

将

管理员

连接到其他两个表的并集，

按管理员分组

和

掩码

并聚合：

select a.admin_username username, t.mask, sum(maskcount) ttlcount
from admins a inner join (
  select 
    table2mask mask, 
    table2adminid adminid, 
    table2maskcount maskcount 
  from table2
  union all
  select * from table3
) t on t.adminid = a.admins_id 
group by a.admins_id, a.admin_username, t.mask

请参阅。
结果:

---

将

admins

连接到其他两个表的并集，

group by admin

和

mask

并聚合：

select a.admin_username username, t.mask, sum(maskcount) ttlcount
from admins a inner join (
  select 
    table2mask mask, 
    table2adminid adminid, 
    table2maskcount maskcount 
  from table2
  union all
  select * from table3
) t on t.adminid = a.admins_id 
group by a.admins_id, a.admin_username, t.mask

请参阅。
结果:

见：见：