分组不使用2个字段总和

Question

我有2张桌子

表1：商店

Id  qty  department
1   20   1
2   10   1
3   05   2

表2：store_sub

Id   parent_id  sub_qty
1    1          5
2    1          6
3    3          9

我想生成适合这种格式的行：

Id  department  qty  sub_qty
1   1           30   11
2   2           05   09

我目前有以下SQL查询：

Select store.id,
  store.department,
  sum(store.qty),
  sum(sub_qty)
from store
  left join store_sub on store_sub.parent_id = store.id
  Group by department

然而，它无效。

如何获得所需的输出？

Answer 1

问题是{1} {id 1}在store表中有两个相应的记录，这意味着store_sub字段将对商店1出现两次。您需要对2个表进行求和分别在子查询中加入相加的版本：

qty

Answer 2

Select store.id, store.department, sum(qty),
sum((select sum(sub_qty) from store_sub where parent_id = store.id group by parent_id )) as sub_qty
from store Group by department